Tvrdi disk (engl. Hard Disk, prevodi se i kao kruti disk ili čvrsti disk) sekundarna je jedinica za pohranu podataka u računalima. Tvrdi diskovi su se pojavili na tehnološkoj sceni 1956. godine, kao izum tvrtke IBM, i nakon svog izlaska na tržište postala dominantna tehnologija za sekundarno pohranjivanje podataka u tipičnim računalnim sistemima tokom 1960-tih. Danas (2019.) tvrdi diskovi rabe se u mnogim računalnim sustavima, a nedavne inovacije u tehnologijama kao tvrdi diskovi bez pokretnih koji rabe tehnologije flash memorija i NAND tehnologije, polako počinju potiskivati magnetske diskove s pojedinih sustava kao što su prijenosnici. Tvrdi diskovi zbog neprekidnog razvoja i usvajanja novih tehnoloških rješenja još su najprivlačniji kao tehnologija za sekundarno pohranjivanje podataka što se tiče odnosa sljedećih svojstava: nosivosti, brzine prijenosa podataka i cijene.

mini|250px|Razne generacije tvrdih diskova

Tehnička svojstva

Tvrdi diskovi sastoje se od jedne ili više kružnih ploča zatvorenih u hermetičkom kućištu. Ove kružne ploče vrte se oko jedne središnje osi uz pomoću elektromotora. Ploče su obično napravljene od legure nekog metala (željeza, aluminija, ili neke druge kombinacije) dok kod nekih tvrdih diskova ploče su izrađene od stakla. U procesu izrade ploče se obično presvlače tankim slojem neke feromagnetske tvari. Čitanje i zapisivanje podataka vrši se uz pomoć posebne magnetske glave koja lebdi tik iznad magnetskog sloja. Kod tvrdih diskova s više ploča, magnetske glave su na svakoj ploči, i nekada s obje strane ploče. Magnetske glave postavljaju se na posebne nosače kojima upravlja posebni mehanizam i upravljačka jedinicom. Podatci koji se zapisuju odnosno čitaju preko magnetskih glava podatke rabeći razne kodne i modulacijske sustave (FM, MFM, MMFM). Prednost tvrdih diskova jest da se podatci mogu čitati:
 u slijedu, jedan za drugim, ili
 van reda s bilo koje točke gdje magnetska glava može dostići.

Ova osobnost pristupa van reda, dovela je do revolucije u obradi podatataka na računalnim sistemima, jer više nije bilo potrebno čitati magnetske trake od početka do mjesta gdje se nalaze podatci ili čitati bušene kartice koje su zauzimale mnogo prostora i na koje nije bilo moguće spremiti mnogo podataka. Ova inovacija omogućila je razvoj novih operacijskih sustava, kao i razvoj novih aplikacijskih programa u kojima podatci se mogu obraditi u stvarnom vremenu.

Kapacitet

Kapacitet tvrdih diskova uvjetovano je različitim faktorima, i mijenjala se tokom razvoja tehnologije od svoje pojave na tržištu 1956. godine. Primjerice prilikom razvoja prvog tvrdog diska IBM-ovi inženjeri mogli su razviti tvrdi disk većeg obujma, no prodajni stručnjaci bili su uvjereni da tržište nije sposobno primiti disk s većim obujmom. Kapacitet nekog tvrdog diska uvjetovana je sljedećim:
 kvalitetom magnetske tvari kojim su presvučene magnetske ploče i gustoće magnetske tvari,
 veličinom magnetske glave koja uvjetuje širinu trake, te
 tehnologijom zapisivanja (FM, MFM, MMFM)

S poboljšavanjem tehnologije tijekom vremena, kapacitet tvrdih diskova povećavala se sukladno Mooreovom zakonu koji je prikazan na dijagramu. Od pojave tvrdog diska 1956. godine koja je tada imao kapacitet od 5MB, kapacitet diskova brzo je rasla no trebala je 51 godina (2007.) da kapacitet tvrdih diskova stigne 1TB (Tera bajta), dok za skok od 1TB do 2TB trebalo je samo godinu dana.
mini|desno|500px|Kretanje rasta kapaciteta podataka od 1956. godine do 2009. i usporedba prema Mooreovom zakonu rasta. Y-os je kapacitet u GB/kvadradnom colu, dok je X-os godina. Mooreov zakon je prikazan u mangenti.

Vrijeme pristupa podatcima

Tvrdi disk je elektronsko-električno mehanički uređaj koji ima određena svojstva koje utječu na pristup odnosno na spremanje podataka. Brzina vrtnje ploča presvučenih magnetskim tvarima, brzina pomicanja čitačko/pisače magnetske glave s trake na traku, prijenos podataka s magnetske glave s i na magnetsku tvar, te prijenos podataka prema i od računala su samo dio svojstava koje utječu na vrijeme pristupa podatcima na nekom tvrdom disku. Tri osnovne značajke koje utječu na prijenos podataka jesu:
 latentnost,
 vrijeme traženja, te
 brzina prijenosa podataka.

Mnogi dizajneri i proizvođači imaju svoja specifična tehnološka rješenja za navedene značajke, no u mnogo puta krajnje vrijeme pristupa podatcima ograničeno je standardima za međuspoj tvrdih diskova s računarskim sustavom, te fizičkih svojstava kao brzina vrtnje tvrdog diska.

Latentnost

Kod tvrdih diskova, latentnost je vrijeme koje je potrebno da se neki dio koji nosi podatke na disku ponovno pojavi ispod glave za čitanje i pisanje. Latentnost nekog tvrdog diska izravno je povezana s brzinom elektromotora koji pokreće vrtnju ploča s magnetskim premazom. Ovo kašnjenje funkcija je brzine okretanja ploče, i s bržim obrtajem ploča, latentnost se smanjuje. Isto tako latentnost na tvrdom disku uvjetovana je geometrijom traka koji se nalaze na tvrdim diskovima. Zbog raznog broja traka na magnestkoj ploči latentnost na trakama bliže osi okretanja bit će manja, dok će latentnost prema obodima magnestke ploče biti veća. Zato se u literaturi obično rabi prosječna latentnost, jer su magnetske ploče relativno malene u radijusu u odnosu prema brzini okretanja. Sljedeća tablica sadrži prosječno vrijeme latentnosti za pojedine popularne brzine okretaja koji se rabe ili su se rabile za tvrde diskove:
 Brzina obrtanja[rpm] Prosječna latentnost[ms] 15.000 2 10.000 3 7.200 4,16 5.400 5,55 4.800 6,25

Vrijeme traženja

Vrijeme traženja je vrijeme potrebno da se dođe do nekog željenog bloka na tvrdom disku, tj. od trenutka kada se upit poslao prema tvrdom disku, i vrijeme koje je potrebno tvrdom disku da dođe do željene minimalne čestice podataka koja se može spremiti ili čitati s tvrdog diska. Na vrijeme traženja utječu sljedeći faktori:
 brzina vrtnja diska,
 vrijeme da se magnetska glava pomjeri s trake na traku,
 vrijeme da se magnetska glava pomjeri na traženi blok,
 način kojim se zapisivaju blokovi, i
 način na koji se šalje slijed poslova čitanja i zapisivanja podataka

Na vrijeme traženja u velikom utječe i mjesto gdje se magnetska glava nalazi kada se ne čitaju ili pišu podatci, ili način na koji se šalju poslovi da se čitaju ili pišu podatci. Primjerice, ako tvrdi disk miruje i ne postoje poslovi preko kojih se zapisiuju ili čitaju podatci put magnetske glave sigurno će biti smanjen ako (npr.) magnetska glava lebdi na središnjoj traci umjesto da stoji na obodu ploče ili blizu središnjice ploče. Isto tako prilikom mnogostrukih čitanja ili pisanja, izvršavanje poslova (čitanja i pisanja) prema slijedu na koji se ti poslovi pojavljuju nekada nije najbolje riješenje. Mnogi dizajneri tvrdih diskova kao i operacijskih sustava izmislili su algoritme u kojima pokušavaju smanjivati naglo pomicanje magnetskih glava od oboda do središnjice u cilju da se smanji vrijeme traženja na tvrdim diskovima.

Brzina prijenosa podataka

Postojanost i kvarovi

 Princip rada

Magnetski disk svoje djelovanje temelji na fizičkim osnovama magnetskog polja i svojstvima feromagnetskih materijala. Pri upisu podataka na njega koriste se svojstva takozvanih tvrdih feromagnetskih tvari da nakon što su magnetizirane vanjskim poljem, ostanu magnetizirane i nakon što se vanjsko magnetsko polje ukloni.

Tvrdi disk se sastoji od nekoliko ploča obično od nemagnetskih materijala, najčešće legure aluminija ili stakla. Te ploče su premazane tankim slojem feromagnetskog materijala debljine 10 do 20 nm (za usporedbu, debljina običnog kopirnog papira je između 0,07 mm i 0,18 mm - 70.000-180.000 nm).http://hypertextbook.com/facts/2001/JuliaSherlis.shtml Na taj magnetski materijal se obično još stavi premaz ugljika kao zaštitni sloj. Za magnetski materijal se danas obično biraju legure kobalta, dok su ranije bili korišteni oksidi žeǉeza, kroma, ili slično.

mini|lijevo|250px|Unutrašnjost tvrdog diska nakon uklanjanja magnetskih ploča. Lijevo gore je pogon magnetske glave za čitanje i pisanje. U sredini desno se mogu vidjeti navoji statora elektromotora koji okreće magnetske ploče.

Disk se okreće oko svojeg središta brzinom od 3000 okr./min. do 10.000 okr./min., dok se tik iznad njega nalazi glava za čitanje i pisanje (engl. read-and-write head), pričvršćena na ručku koja može glavu premjestiti bliže ili dalje središtu diska. Na današnjim, modernim diskovima, udaljenost te glave od površine ploče se mjeri u nanometrima.

mini|250px|desno|Tvrdi disk rastavljen u sastavne dijelove

Pohranjivanje i čitanje podataka

Podaci se na disk upisuju uz pomoć male zavojnice koja je sastavni dio glave. Zavojnica u biranim trenucima propušta električnu stuju izabranog smjera (princip binarnog sustava, 0 ili 1). Magnetska glava sastoji se od zavojnice koja je namotana na tvrdu feritnu jezgru. Glava je učvršćena na ručicu koju po disku pomiče aktuator. Uz pomoć njega glava se može pomicati iznad cijelog polumjera diska. Magnetska površina ploče u disku podijeljena je u puno malih magnetskih područja veličine mikrometra, a svaka od tih površina se rabi za pohranu (kodiranje) jednog bita informacije. Do 2005. ta podjela magnetske površine bila je samo vodoravna, ali od tada pa do danas ta podjela je i okomita čime su se dobili tvrdi diskovi većeg kapaciteta (do 2 TB). Zbog prirodne kristalne strukture magnetskih materijala, ta područja na disku se sastoje do nekoliko stotina magnetskih čestica (jedna magnetska čestica je veličine 10 nm).

Protjecanjem struje kroz zavojnicu stvara se magnetsko polje koje se zbog blizine glave proteže i kroz magnetski materijal na površini diska. Kako se disk brzo okreće ispod glave, sav materijal koji prođe ispod glave se magnetizira u smjeru određenom smjerom protjecanja električne struje. Uključivanjem struje u kratkotrajnim biranim trenucima, postiže se na površini diska niz različito magnetiziranih područja jedno iza drugog, čime je na disk zapisan niz podataka tj. bitova. Podaci su na disku nalaze kao niz magnetskih čestica na magnetskom sloju diska koje su smještene u koncentrične krugove.

Čitanje se ispočetka radilo koristeći činjenicu da kada niz različito magnetiziranih područja brzo prođe ispod zavojnice magnetske glave, u zavojnici se inducirao električni napon kod svake promjene polja. Inducirani napon i tako dobivena struja ima svoju jakost koja ovisi o jakosti magnetskog polja, njegovom smjeru, brzini promjene magnetskog polja ispred glave i udaljenosti glave od diska. Zbog razlike u induciranom naponu na zavojnici u određenom trenutku dobiva se naponski signal. Iz tog naponskog signala se stoga može zaključiti kakav je raspored magnetiziranih područja prošao ispod nje i time se niz bitova pročitao. No danas se koriste druge magnetske pojave, recimo osobine da prisutnost magnetskog polja mijenja električnu otpornost nekih materijala. Kod takvih diskova, glava je magnetnootporna. Prilikom prolaska čitača glave preko magnetizirane površine diska, glava mjenja svoj električni otpor zbog promjene jačine i smjera magnetskog polja (tehnologija gigantskog magnetootpora (GMR)).

thumb|lijevo|Mnogostruke magnetske glave za zapisivanje i čitanje podataka učvršćene na ručicu

U današnjim (2015.) tvrdim diskovima glave za čitanje i pisanje su odvojene, za razliku od starih diskova na kojima se sve obavljalo uz pomoć jedne glave. Čitača glava je magnetnootporna, dok je pisača glava tankoslojna induktivna.
mini|desno|250px|Izgled magnetskog zapisa na disku tvrdog diska zapremine 200MB (slika je napravljena pomoću uređaja CMOS-MagViewhttp://www.magneticmeasurements.com/cmos-magview.html CMOS-MagView instrument za vizualizaciju magnetskih zapisa

Fizička organizacija podataka

mini|lijevo|Fizička organizcija ploče tipičnog tvrdog diska: A-trakaB-sektorC-sektor između trakaD-grozd (eng. cluster)

Ploča

Sektor

Traka

Blok

Grozd

Radne značajke

Ostale značajke

Dobra i negativna svojstva magnetskog diska

Dobra svojstva magnetskog diska jesu:

 veliki kapacitet,
 postojanost podataka, te
 brzi pristup podacima.

Negativna svojstva jesu:

 osjetljivost na prljavštinu i elektromagnetska polja i
 ograničenje maksimalne gustoće podataka.

Magnetski disk je posebno osjetljiv na elektromagnetska polja i pri rukovanju treba to imati na umu.

 Logička struktura

Postoje razne logičke strukture koje se rabe za spremanje podataka na tvrdim diskovima. Primjerice logička struktura FAT dijeli tvrdi disk na sljedeće dijelove:

 Master boot record (MBR) veličine 512 bajtova, inače prvi sektor na disku na fizičkoj lokaciji: cilindar=0, glava=0, sektor=1. Ova pozicija na disku sadrži:  Master Partition Table (glavnu tablicu podijela na disku) GTP i Master Boot Code (glavni kod za pokretanje) GKP. GTP je također poznat kao fdisk tablica. Zbog ograničene veličine MBR-a od 512 bajtova, moguće je napraviti samo četiri podjele.http://multiboot.solaris-x86.org/ii/4.html Master Boot Record (MBR), pristupljeno 2. lipnja, 2015.
 Boot Record (datoteka za pokretanje) (sadrži informacije i datoteke potrebne za podizanje/pokretanje operativnog sustava),
 FAT1 i FAT2 (sadrže tablice datoteka te njihovu lokaciju unutar podijele),
 Boot directory (bilježi strukturu direktorija na podijele)
 te najveći dio DATA u kojem su pohranjeni podatci.

 Boot (pokretni) sektor Rezervirano sektori (izborno) FAT #1 FAT #2 Korijenski direktorij (rabi se samo za FAT12/16) Podatkovna oblast  (ostatak diska)

 Povijest razvoja tvrdih diskova

Prvi tvrdi disk razvila je tvrtka IBM 1956. za računalo IBM 305 pod imenom IBM 350 Disk File. Ovaj prvi tvrdi disk sastojao se od pedeset 24 inčnih magnetskih ploča i imao je zapreminu od 5 milijuna 7-bitnih znakova (~4,4 megabajta). Za 350 Disk File, IBM je naplaćivao godišnju najamninu od USD $35.000. Prvi tvrdi disk mogao je imati i veću zapreminu, jer su tehnološka rješenja to omogućavala no veća nosivost bila je odbijena od rukovodstva tvrke IBM jer navodno prodajni odjel nije vjerovao da bi mogli prodati tvrdi disk veće zapremine, zbog navodnoe nespremnosti tržišta za veću jedinicu.Lee Gomes, "Talking Tech" The Wall Street Journal, 22. kolovoza, 2006   Godine 1962. tvrtka IBM je na tržište iznijela novi model tvrdog diska 1311, koji je imao fizičke dimenzije stroja za pranje rublja, dok su se podatci pohranjivali na zamjenjivim diskovnim svežnjevima zapremine od 2 milijuna 7-bitnih znakova. Zamjena diskovnih svežnjeva omogućavala je korisnicima proširivanje spremišnih mogućnosti. Jedinice u kojima se nisu mogle promijeniti diskovni svežnjevi zvali su se učvršćeni tvrdi diskovi.

Mnoge inovacije su nastale tokom vremena, kao recimo jedna glava po traci za tvrde diskove koje su imale visoke zahtjeve s pristup (npr. IBM 2305), no zbog skupće njihove izrade ove jedinice nisu bile dugo prisutne na tržištu.Computer Organization and Design, 2nd Ed., P. Pal Chaudhuri, 2006,p. 635

IBM je 1973. godine unio inovaciju na tržištu s proizvodom IBM 3349 Winchester, u kojem su IBMovi inženjeri uspjeli smanjiti kompleksnost magnetskih glava tako što se magnetske glave više nisu povlačile potpuno s magnetskih ploča već su prilikom pokretanja ili kada bi se tvrdi disk trebao ugasiti magnetske glave su bile micane na posebno određeno mjesto na ploči. Ova inovacija je u mnogome pomogla smanjivanja cijene tvrdim diskovima. Jedan od prvih modela imao je zamjenjive svežnjeve. Ovi zamjenjivi svežnjevi imali su inovaciju da su sadržavali cijeli podsklop i mehanizam za micanje magnetskih glava. Kasnije s razvojem tehnologije i gustoće nosivosti, IBM i ostali proizvođači krutih diskova su napustili tehnologiju zamjenjivih svežnjeva.

 Povijest po godinama od 1980. do danas

 1980. - prvi disk kapaciteta 1 GB, IBM 3380, veličine hladnjaka, težak oko 250 kg, i cijene 40.000 USD.
 1986. - standardizacija sučelja SCSI
 1998. - standardizacija pristupa UltraDMA/33 i ATAPI
 2002. - adresiranje preko 137 GB diskovnog prostora
 2003. - uvođenje standarda SATA
 2005. - prvi tvrdi disk kapaciteta 500 GB  (Hitachi)
 2005. - standardizacija Serial ATA 3G
 2005. - uvođenje standarda SAS (Serial Attached SCSI)
 2005. - tvrtka Toshiba uvodi okomito zapisivanje
 2006. - prvi disk kapaciteta 750 GB (Seagate)
 2007. - prvi disk kapaciteta 1.000 GB (1 TB - terabajt) Hitachi
 2008. - prvi disk kapaciteta 1,5 TB (Seagate)
 2009. - prvi disk kapaciteta 2 TB (Western Digital)
 2010. - prvi disk kapaciteta 3 TB (Seagate)

mini|250px|desno|Usporedba između fizičke veličine i podatkovne zapremine tvrdih diskova u formatu 5,25 cola (110 MB) i 2,5 cola (6.495 MB)

 Budućnost tvrdih diskova

Zapremina mnogih današnih tvrdih diskova (2015.) približavaju se 1 TB po kvadratnom colu, Bruno Marchon, Thomas Pitchford, Yiao-Tee Hsia, i Sunita Gangopadhyay2The Head-Disk Interface Roadmap to an Areal Density of Tbit/in2, Advances in Tribology Volume 2013 (2013), Article ID 521086, 8 pages, http://www.hindawi.com/journals/at/2013/521086/ pristupljeno: 2. lipnja 2015. a razvojem raznih tehnologija za magnetske glave, te novih tehnologija za zapisivanje podataka, te ispunjavanja unutrašnjosti inertnim plinovima i još nekim drugim inovacijama omogućit će gustoće zapisivanja i do 4 TB po kvadratnom colu magnetskog medija.

Standardne veličine tvrdih diskova

+ Bivši i sadašnji obrasci za tvrde diskove Obrazac Stanje Dužina [mm] Širina [mm] Visina [mm] Kapacitet Broj ploča (maks.) ZapreminaPo ploči [GB] 3,5-cola  146 101,6 19 ili 25,4 8 TB http://www.hgst.com/press-room/press-releases/HGST-unveils-intelligent-dynamic-storage-solutions-to-transform-the-data-center 8TB HDD Now Shipping ...(2014.) 5 or 7http://www.hgst.com/hard-drives/enterprise-hard-drives/enterprise-sas-drives/ultrastar-he6 Ultrastar He6: 6TB 3.5-inch Helium Platform  2,5-cola  100 69,85 5http://www.engadget.com/2012/09/10/western-digital-builds-5mm-thick-hybrid-hard-drive/ Western Digital builds 5mm-thick hybrid hard drive, Ultrabook makers sign on early 7, 9.5, 12.5, 15, ili 19{http://www.4drives.com/DRIVESPECS/QUANTUM/3364.txt  Quantum Go*Drive specifications 2 TBhttp://www.wdc.com/en/products/products.aspx?id=830#Tab3 Western Digital WD20NPVX Specifications 4 667http://www.seagate.com/www-content/support-content/samsung/internal-products/spinpoint-m-series/en-us/samsung-m9t-internal-ds.pdf Samsung M9T Mobile SATA Drive Datasheet 1,8-cola  78,5 54 5 ili 8 320 GB http://www.toshiba.co.jp/about/press/2009_11/pr0501.htm(2009.) 2 220  http://storage.toshiba.com/techdocs/MKxx39GSL_Data_Sheet.pdf 8-cola  362 241,3 117,5 5,25-cola FH  203 146 82,6 47 GBSeagate Elite 47, shipped 12/97 per 1998 Disk/Trend Report – Rigid Disk Drives (1998.) 14 3,36 5,25-cola HH  203 146 41,4 19,3 GBQuantum Bigfoot TS, shipped 10/98 per 1999 Disk/Trend Report – Rigid Disk Drives (1998.) 4 4,83 1,3-cola  43 40 GBhttp://www.sdk.co.jp/aa/english/news/2008/aanw_08_0812.html , SDK Starts Shipments of 1.3-Inch PMR-Technology-Based HD Media (2007.) 1 40 1-cola (CFII/ZIF/IDE-Flex)  42 20 GB (2006.) 1 20 0,85-cola  32 24 5 8 GBhttp://digitaljournal.com/article/117340 Proving that 8 GB, 0.85 inch hard disk drive existshttp://www.toshiba.co.jp/about/press/2004_03/pr1601.htm Toshiba Enters Guinness World Records Book with the World's Smallest Hard Disk Drive (2004.) 1 8

8 cola

5,25 cola

3,5 cola

2,5 cola

 Pristup podacima ili adresiranje

Razvoj metoda adresiranja bio he uvjetovan vremenom i tehnološkim rješenjima (sklopovlje i operacijski sustav). Od pojave tvrdih diskova na tržištu (1956.) razvijene su sljedeće tehnike za pristup podatcima:

 CHS (cylinder, head, sector) - cilindar, glava, sector

 ECHS (Extended cylinder, head, sector)- produženi cilindar, glava, sector

 LBA (Logical Block Adressing) - pristup preko logičkih blokova

 MZR (Multiple Zone Recording) - snimanje kroz mnogostruke zone

 CKD Count Key Data - brojanje ključnih podataka

 ECKD Enhanced CKD - prošireni CKD

 Međusklopovi
 ST-412/506
Ime ST506 ima povijesno značenje, naime tvrtka Seagate je 1980. godine uvela taj međusklop sa svojim tvrdim diskovima od 5 megabajta, i precizno je definirala sučelje prema kontroleru. Godinu dana kasnije došao je novi model, ST412 i diskovi od 10 megabajta. IBM je prihvatio ideju, i to sučelje danas znamo pod imenom ST412/506.

Zbog ograničene brzine prijenosa podataka (za MFM 5 megabita/s, za RLL 7,5 megabita/s), mogućnosti priključivanja samo dva diska u jednom računalu, sučelje je uskoro napušteno.

 ESDI
ESDI je sučelje tvrtke Maxtor nastalo 1983. godine. Omogućava maksimalnu brzinu od 24 megabita u sekundi. Također, na taj način je bilo moguće spojiti sedam diskova u jednom računalu, ali sučelje nije zaživjelo.

 ATA
 IDE - kratica za intelligent drive electronics, donio je nova povećanja brzina prijenosa, ali samo dva diska u računalu.
 EIDE - enhanced ili poboljšani IDE, 4 diska + povećane brzine prijenosa podataka
 PATA - paralelni ATA
 SATA - serijski ATA

mini|desno|250px|Pogled na unutrašnjost tvrdog diska tvrtke Seagate ST33232A iz 1998. godine, koji rabi paralelni ATA međusklop PATA

 SCSI
 SCSI (small computer systems interface) donosi od početka 7 diskova u računalu, kasnije novim standardima (SCSI II, Fast SCSI i Wide SCSI) i 15 SCSI jedinica u računalu
 SCSI II
 Fast SCSI
 Wide SCSI

SCSI nije sučelje ograničeno samo na tvrde diskove/optičke pogone kao ST412/506, ESDI i IDE/EIDE, već je na SCSI također moguće priključiti i vanjske jedinice poput preslikača (skenera).

 Nobelova nagrada

Albert Fert i Peter Grünberg dobili su Nobelovu nagradu za fiziku za otkriće divovskog magnetootpora (GMR) - zasebno su došli do tog otkrića 1988. godine. Ta se tehnologija danas rabi u svim tvrdim diskovima.

 Vrela

 Vanjske poveznice

Kategorija:Sklopovlje
Kategorija:Pohranjivanje podataka

With the improvement of technology over time, the capacity of the hard drives increased in accordance with Moore's law that was displayed on the diagram.

It took 51 years before hard disk drives reached the size of 1 TB (terabyte, i.e. 1,000 GB). This happened in 2007. In 2009, the first hard drive with 2 TB of storage arrived. So while it took 51 years to reach the first terabyte, it took just two years to reach the second.
This article looks back at how hard disk drives have evolved since they first burst onto the scene in 1956. We’ll examine the radical changes over time for three different aspects of HDDs: Size, storage space, and price.
Changes in physical size over time
The first hard disk drive, like so many innovations in computing, came from IBM. It was called the IBM Model 350 Disk File and was a huge device. It had 50 24-inch disks contained inside a cabinet that was as large as a cupboard and anything but lightweight. This hulk of a storage unit could store a whopping 5 MB of data.
Above: An IBM Model 350 Disk File being delivered. Yes, that’s ONE hard disk drive unit.
Although hard disk drives kept improving, state-of-the art disks were built according to the concept “bigger is better” well into the ‘80s. Hard disk drives were normally used together with big mainframe computers, so this was not such a big deal. Entire rooms were already set aside for the computers.
Case in point, here below is a 250 MB hard disk drive from 1979.
Above: State-of-the-art hard disk drive from the ‘70s.
IBM introduced the first hard disk drive to break the 1 GB barrier in 1980. It was called the IBM 3380 and could store 2.52 GB (500 times more than the consumer options at the time). Its cabinet was about the size of a refrigerator and the whole thing weighed in at 550 pounds (250 kg).
Above: The disk drive module of the IBM 3380.
Early in the ‘80s, smaller “consumer” hard disk drives designed to be used with the increasingly popular microcomputers (now known as PCs) started to appear. The first ones were 5 MB in size and had a form factor of 5.25 inches.
For a visual on how hard disk drive sizes have changed since the ‘80s until today, have a look at the below image with an old 8-inch drive all the way down to today’s 3.5-inch, 2.5-inch and 1.8-inch drives.
Above: Three decades of shrinkage.
Changes in storage space over time
The first hard disk drive back in 1956 could store 5 MB of data, which was a huge amount at the time. This is coincidentally also the size of the first “small” 5.25-inch hard disk drive that arrived in 1980. We went from having to have a special room for the hard disk drive and its computer, to having one we could put inside a desktop computer.
Ten years later, in 1990, a normal hard drive held about 40 MB, with more expensive options able to store more than 100 MB.
Fast forward to present day, and you can buy a 3.5-inch hard disk drive with 2 TB of storage space.
To illustrate the tremendous increase in storage space that we have seen in the last 30 years (essentially since the birth of personal computing), we have made a 1980 vs. 2010 side-by-side comparison chart here below.
Note that we have used a logarithmic scale in this chart. Each step on the Y axis is 10 times larger than the one below it. If we had used a regular, linear scale, the columns for 1980 would have been less than a pixel high.
As you can see, the gap between a normal versus a top-of-the line hard disk drive in terms of storage space has become much, much smaller than in the past. And as an added bonus, they also have the same physical size these days, which they most definitely did not have back in 1980. No one is making those fridge-sized hard disk drives anymore.
Of course, nowadays we have special storage devices with a gazillion regular hard disk drives crammed inside that have taken over the “ridiculously expensive” crown.
And speaking of price…
Changes in price over time
As with any rare commodity, early hard drives were extremely expensive and were used with equally huge and expensive mainframe computers.
The first hard disk drive, the IBM Model 350 Disk File we mentioned above, wasn’t something you got as a stand-alone unit. It wasn’t even something you bought. Instead you could lease the IBM 305 RAMAC computer that came with the 350 Disk File for $3,200 per month. Needless to say, back in ‘50s this was a lot more money than it is now.
The biggest and best hard disk drives kept being an expensive proposition. When it finally started selling in 1981 after some initial delivery hickups, the price for the 2.52 GB refrigerator-sized IBM 3380 started at $81,000. And then you of course needed a computer to use it with…
The first 5.25-inch 5 MB hard disk drives (i.e. the consumer option) in the ‘80s cost well over $3,000. Similar prices remained for the 10 MB drives that soon replaced them. This probably explains why most PCs were initially sold without a hard disk drive, instead relying on floppy disk drives.
As storage space has increased, it has also become infinitely more affordable. The average cost per GB has over the last 30 years gone from way over $100,000 to just a few cents. Now that’s inflation…
Factoid: A 5 MB hard disk drive from Apple cost $3,500 in 1981. That’s $700,000 per GB.
And of course, 30 years ago most people couldn’t get their hands on 1 GB of storage even if they tried.
A promotion video of the first hard drive
To round off this retrospective, here is some vintage promotion material about the 1956 IBM 305 RAMAC computer and its amazing new innovation, the IBM 350 Disk File. This is tech geek gold. If you can watch this without getting a smile on your face, please get some help. 😉
Another 30 years into the future
Considering that we now have tiny, cheap USB sticks that can hold up to 64 GB of data, which is about 1,600 times more than a normal hard disk drive in 1990 (40 MB), and 12,800 times more than the first consumer hard disk drive in 1980, things have certainly moved forward.
And just like we are now looking back and shaking our heads at the amazing difference between now and a few decades ago, we will, thirty or so years from now, look back at 2010 and shake our heads with similar amazement. “Was storage really that primitive back then?”
Picture Sources:
The IBM 350 Disk File from IBM via ed-thelen.org. 250 MB hard disk drive from 1979. Hard disk drives of multiple sizes by Paul R. Potts. IBM 3380 disk drive module by ArnoldReinhold (Wikimedia Commons). Closeup of HDD head by Alexdi (Wikimedia Commons).
Wikipedia was, as it so often is, a great help when checking out the facts and figures.
3 comments
Great Article, really puts things in perspective.
It would be helpful if you could post some information on the evolution of disk speed I/O since the 1960’s ? As I understand it the disk speed have increased 4,5x but I cant find any sources that clarifies that….
looking fwd to my 1st Peta SSD.
Thaanx for a great article………..

Question: the capacity of a tvrdi disk increased due to advances in technology and what

the capacity of a tvrdi disk increased due to advances in technology and what

Question: what happened to the capacity of the tvds

what happened to the capacity of the tvds

Question: what is the main cause of the increase in capacity of tvds

what is the main cause of the increase in capacity of tvds

Question: which law states that the capacity of a tvrdi disk increases with advances in

which law states that the capacity of a tvrdi disk increases with advances in

Question: where is moore's law located on a cd

Question: who developed the theory of the capacity of a tvldi disk

who developed the theory of the capacity of a tvldi disk

Question: what is the effect of technology on a tvds disk

kapacitet tvrdih diskova povećavala se sukladno Mooreovom zakonu koji je prikazan na dijagramu

what is the effect of technology on a tvds disk

Question: what is the main component of a tv3 disk

tvrdih diskova povećavala se sukladno Mooreovom zakonu koji je prikazan na dijagramu

what is the main component of a tv3 disk

With the improvement of technology over time , the capacity of the hard drives increased in accordance with Moore 's law that was displayed on the diagram .

The hard disk consists of several plates usually of non-magnetic materials, most often alloys of aluminum or glass.

Thickness of a Piece of Paper
An educational, fair use website
|Bibliographic Entry||Result
|
(w/surrounding text)
|Standardized
|
Result
|Common Paper Sizes. papershops.com.||"Copy paper is about 0.004 inches thick"||0.1 mm|
|Basford, K.E., G.J. Mclachlan & M.G. York. Modeling the distribution of stamp paper thickness via finite normal mixtures: The 1872 Hidalgo stamp issue of Mexico revisited. Journal of Applied Statistics. Vol. 24, No. 2 (April 1997): 169-180.||"As noted by Izenmend and Sommer, there is some clustering around the value 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, and 0.13 mm, with about half the data between 0.06 and 0.08."||0.07–0.13 mm|
|Average Paper Thickness (in 1/1000 in.). National Printing Source. Commercial Printers Helper.|
|0.076–0.18 mm|
|University of the State of New York Regents. High School Examination in Physics. Thursday June 5, 1989.|
|0.1 mm|
|International Paper, 8½ × 14 in 216 × 356 mm, Legal, 75 g/m sq, 20/16, 500 sheets, white.||[Measured thickness of 500 sheets is 51.5 mm]||0.103 mm|
Paper…. What is paper? Well, to most, including myself, it's simply something we use to record all of our notes and data. Sometimes we use it just to draw and doodle something while we talk on the phone or are bored out of our minds. Most of a time, I don't think any of us sit there thinking about its value, we simply use it and that's all. However, if you really think about it, what would we do without it. Paper is one of the most significant products, used in various fields of our social and industrial lives. We use it to communicate to each other through mail, nearly all of our reading material is made out of paper, tissues, bags, and even money is made out of paper. Many times we waste paper without even thinking about its importance and its special qualities. In the beginning for example, before paper was even made, people used clay as their writing material.
Then first form of paper was made from a plant called papyrus. Its fibers were turned into paper, but it was far from the paper we use today. Paper today, doesn't only vary in its texture, size and color, but also in its caliper or in the other words thickness of a piece of paper expressed in thousandth of an inch. Although as I have already mentioned there are various types of paper, the average thickness of a regular copy paper ranges from 0.05 to 0.10 millimeters. It's obviously much thinner than the old fashioned papyrus and way more lighter than clay. All of this is thanks to our advanced technology. Don't you think it would be pretty sad if instead of light pieces of loose-leaf paper, we literally had to carry stones in our bags or old yellow papyrus? I'm guessing your answer would be "yes"!
Julia Sherlis -- 2001

Question: what are the components of a tvrdi disk

The hard disk consists of several plates usually of non-magnetic materials, most often alloys of aluminum or glass.

Question: what is the thickness of a tvrdi disk

10 do 20 nm ( za usporedbu , debljina običnog kopirnog papira

Question: what type of materials are on a tvrdi disk

what type of materials are on a tvrdi disk

Question: what type of material is on the hard disk

materijala debljine 10 do 20 nm ( za usporedbu , debljina običnog kopirnog

what type of material is on the hard disk

The hard disk consists of several plates usually of non - magnetic materials , most often alloys of aluminum or glass .

These plates are covered with a thin layer of feromagnetic material of a thickness of 10 to 20 nm ( for comparison , the thickness of ordinary copy paper is between 0.07 mm and 0.18 mm - 70.000 - 180.000 nm ) .

Tvrdi disk se sastoji od nekoliko ploča obično od nemagnetskih materijala, najčešće legure aluminija ili stakla.

The hard disk consists of several plates usually of non-magnetic materials, most often alloys of aluminum or glass. These plates are covered with a thin layer of feromagnetic material of a thickness of 10 to 20 nm (for comparison, the thickness of ordinary copy paper is between 0.07 mm and 0.18 mm - 70.000-180.000 nm).

The hard disk consists of several plates usually of non-magnetic materials, most often alloys of aluminum or glass.

The reading of the beginning was done using the fact that when a series of differently magnetized areas quickly pass under the magnetic head curve, the curve was induced by electric voltage at each field change.

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The era of giant magnetoresistive heads
Hitachi's magnetoresistive and giant magnetoresistive head technologies enable data storage products with the industry's
highest areal densities.
By Jim Belleson, (title) and Ed Grochowski, (title)
Introduction
Magnetic hard disk drives (HDDs) continue to be the primary, high performance storage technology in terms of bytes shipped per year. The success of HDDs originates from an ever increasing demand for storage capacity coupled with a consistent reduction in price per megabyte. Areal density (expressed as billions of bits per square inch of disk surface area, Gbits/in²) is the product of linear density (bits of information per inch of track) multiplied by track density (tracks per inch), and varies with disk radius. It is often valuable to quote areal density in terms of its maximum value. Improved areal density levels have been the dominant reason for the reduction in price per megabyte. Figure 1 shows the 60% compound annual growth rate (CGR) in areal density for Hitachi HDD products. If this CGR continues, areal densities of 10 Gbits/in² and 40 Gbits/in² are expected by the years 2001 and 2004 respectively. High areal densities have been achieved by introducing new technology and by proportionally reducing certain key dimensions within the HDD ("scaling"). The most significant advancements have been the magnetoresistive (MR) head, the extended magnetoresistive head (MRx) head, and the follow-on giant magnetoresistive (GMR) head technologies.
In 1991, IBM pioneered the use of MR heads for disk drives with the 1 Gigabyte (GB), 3.5-inch IBM 0663-E12 drive, which provided the highest areal density available at the time. In 1994, using MR heads, IBM Research demonstrated an areal density of 3 Gbits/in² and about 3 years later, in 1997, IBM started manufacturing 3 Gbits/in2 MR heads in volume. In 1996, IBM Research demonstrated an areal density of 5 Gbits/in² using an advanced MR head1. It would be expected that laboratory investigations continue at IBM to achieve even higher areal densities using more advanced head designs, i.e. GMR.
The GMR effect was discovered in 1988 in perfect-crystal samples exposed to very high fields (1000 times the fields used in HDDs)². In that same year an initial concept for using the GMR effect in magnetic recording was disclosed3. By 1991, work at IBM's Almaden Research Center opened the door for affordable applications by showing the spectacular GMR effect could also be achieved in more-easily-made sputtered, polycrystalline multilayer samples. By 1991 IBM Research also developed GMR structures, named "spin valves", that responded to the much smaller magnetic fields produced by written data in a HDD4. In 1994, IBM Research announced it had created the world's most sensitive sensor for detecting computer data on magnetic hard disks using the GMR effect5. In December 1997, IBM announced a 16.8 Gbyte 3.5-inch HDD product using GMR heads for the high performance desktop market, the industry's first GMR storage product and with an areal density of 2.69 Gbits/in² , the highest for that form factor. In early 1998 IBM announced and began production of a 6.48 Gbyte 2.5-inch HDD designed for the mobile computer market with an areal density of 4.10 Gbits/in² using GMR heads, another industry first. Concurrent with this, IBM announced that a GMR spin valve head with an areal density capability of 11.6 Gbits/in² was under investigation, and that this advanced head was produced using much of the existing processing facilities available for today's production heads6.
The primary advantage of GMR heads is greater sensitivity to magnetic fields from the disk. This increased sensitivity makes it possible to detect smaller recorded bits and to read these bits at higher data rates. Larger signals from GMR heads also help overcome electronic noise. GMR heads are expected to support areal densities beyond 11.6 Gbits/in² and it is projected that GMR will become the dominant head technology for the years beyond 2000.
The high areal densities attainable with MR and GMR heads enable
disk drive products to offer a maximum storage capacity with a minimum
number of components heads and disks. Fewer components translates
to lower storage costs, higher reliability, and lower power requirements.
In 2003, Hitachi Global Storage Technologies was founded as a result
of the strategic combination of IBM and Hitachi’s storage
technology businesses and technologies, such as giant magnetoresistive
heads.
Hitachi Global Storage Technologies continues to lead the industry
in areal density advancements. This leadership is due to extensive
research and development efforts at Hitachi's Almaden Research Center
in San Jose combined with the ability to ramp this technology quickly
in manufacturing facilities around the world.
Merged read/write head A proven design
The head design consists of a thin film inductive write element
and a read element (Figure
2). The read element consists of an MR or GMR sensor between
two magnetic shields. The magnetic shields greatly reduce unwanted
magnetic fields coming from the disk; the MR or GMR sensor essentially
"sees" only the magnetic field from the recorded data bit to be
read. In a merged head the second magnetic shield also functions
as one pole of the inductive write head.
The advantage of separate read and write elements is both elements
can be individually optimized. A merged head has additional advantages.
This head is less expensive to produce, because it requires fewer
process steps; and, it performs better in a drive, because the distance
between the read and write elements is less.
Magnetic recording process
Figure 3 depicts a merged read/write head flying over a rotating disk. The inductive write head records bits of information by magnetizing tiny regions along concentric tracks. During reading, the presence of a magnetic transition or flux reversal between bits, causes the magnetic orientation in the MR or GMR sensor to change. This in turn, causes the resistance of this sensor to change. The sensor's output voltage or signal is the product of this resistance change and the read bias current. This signal is amplified by low-noise electronics and sent to the HDD's data detection electronics.
MR and GMR sensor technology
HDD designers now have access to MR and GMR sensors, which are both very thin. If 250,000 of these sensors, excluding leads, were stacked on top of each other, the stack would be less than one inch high. The biggest functional difference between MR and GMR sensors is sensitivity, measured by percent change in resistance. In an MR sensor a resistance change is caused by an intrinsic property of the sensing layer. In a GMR sensor, however, a resistance change is caused by the quantum nature of electrons. Figure 4 shows the sensitivity of GMR sensors is more than twice the sensitivity of MR sensors.
MR and GMR sensors are composed of multiple thin films (Figures 2, 5, and 6.). Both sensors have a sensing layer which responds to external magnetic fields. In the absence of an external magnetic field, this sensing layer will spontaneously magnetize itself parallel with the long axis of this layer, which is parallel to the disk. A fixed magnetic field ("horizontal bias") is also applied in this direction by hard bias films to establish a single magnetic domain in the sensing layer. This single magnetic domain minimizes domain noise and promotes consistent reading. This sensing layer's magnetic orientation, referenced to the disk, rotates from parallel to perpendicular when an increasing perpendicular magnetic field ("transverse magnetic field") is applied. This field is composed of a varying external magnetic field from the rotating disk and fixed internal magnetic fields ("transverse bias") from other parts of the sensor.
MR sensor basics
In a typical MR material, e.g. a nickel-iron alloy, conduction electrons move less freely (more frequent collisions with atoms) when their direction of movement is parallel to the magnetic orientation in the material- the "MR effect". When electrons move less freely in a material, the material's resistance is higher.
The MR sensor's sensing layer is MR material. When no transverse
magnetic field is applied, this sensing layer's magnetic orientation
is parallel to the disk and to the electron flow; therefore, the
resistance of the sensing layer is higher. A transverse magnetic
field can then rotate the sensing layer's magnetic orientation producing
lower resistance (Figure 7).
However, equal positive or negative values of transverse magnetic
field will produce the same sensing layer resistance. To avoid this
ambiguity, transverse bias is applied to keep the transverse magnetic
field always positive or always negative. Hitachi has developed
a unique, patented soft-adjacent layer (SAL) structure that provides
transverse bias.
GMR sensor basics
Hitachi has developed GMR sensors composed of four thin films:
a sensing layer, a conducting spacer, a pinned layer, and an exchange
layer. The first three of these films are very thin, allowing conduction
electrons to frequently move back and forth between the sensing
and pinned layers via the conducting spacer. The magnetic orientation
of the pinned layer is fixed and held in place by the adjacent exchange
layer, while the magnetic orientation of the sensing layer changes
in response to the magnetic field from the disk. As explained below,
a change in the magnetic orientation of the sensing layer will cause
a change in the resistance of the combined sensing and pinned layers.
GMR sensors exploit the quantum nature of electrons, which have two spin directions
spin up and spin down. Conduction electrons with a spin direction parallel to a material's magnetic orientation move freely, producing low resistance. Conversely, conduction electrons with spin direction opposite to the material's magnetic orientation are hampered by more frequent collisions with atoms in the material, producing higher resistance.
The application of this quantum nature of electrons to a GMR sensor is shown in Figure 8. Lower resistance occurs when the sensing and pinned layers are magnetically oriented in the same direction, since electrons with spin direction parallel to this magnetic orientation move freely in both films. Higher resistance occurs when the magnetic orientations of the sensing and pinned layers oppose each other, because the movement of spin up electrons is hampered by one of these magnetic layers and the movement of spin down electrons is hampered by the other layer. The resistance of the sensing layer is also changed by the MR effect, however the GMR effect is dominant. Figure 9 illustrates the GMR sensor's response to a changing transverse magnetic field. To realize the full sensitivity of a GMR sensor, the transverse magnetic field variations must fully utilize the linear portion of the GMR sensor's response curve, as shown in Figure 9. This is accomplished by either changing the slope of this response curve or by adjusting the amplitude of the transverse magnetic field. The slope of this response curve can be changed by changing the thickness of the sensing layer and the amplitude of the transverse field can be changed by reducing the magnetic field from the disk. (The same applies to MR sensors.)
Extension of GMR beyond 10 Gbits/in²
For 10 Gbits/in² and beyond, GMR sensors will need to be
thin enough to fit within the required read gap (gap between the
shields) and sensitive enough to detect the magnetic fields from
written bits of information at these densities. From previous MR
head designs, the maximum sensor thickness for 2.6 Gbits/in²
is 0.08 microns, and the recorded bit length is 0.12 microns. The
maximum length of the read gap is about twice the recorded bit length
for a partial response detection channel (PRML)., and the maximum
thickness of the MR or GMR sensor is 1/3 the read gap length to
allow separation of the sensor and shields. If the current ratio
of bit density to track density is maintained, it is estimated by
scaling that the maximum sensor thickness for 10 Gbits/in²
and 40 Gbits/in² will be roughly 0.04 and 0.02 microns respectively.
Experimental GMR sensors are thin enough to fit into this 10 Gbits/in²
read gap; however, a more advanced sensor may be required to fit
into a 40 Gbits/in² read gap. If track density advances more
rapidly than bit density, the maximum sensor thickness for higher
areal density heads can be relaxed. If everything scales, simple
calculations suggest the percent change in resistance of a sensor
needs to increase proportional to the square root of the areal density,
assuming constant surface velocity and sensor temperature7.
Therefore, it will be necessary to continue to improve GMR sensitivity
as areal densities increase. In the design of a recording system,
involving many head, disk, flying height, and channel tradeoffs,
high sensitivity GMR heads can be used in many ways to enhance areal
density and data rate. It is expected that advancements in head
technology will continue to meet future areal density requirements,
as illustrated in Figure 10.
Manufacturing considerations- MR head experience pays off
The GMR heads used in Hitachi's 11.6 Gbit/in² demonstration
closely resemble heads currently being manufactured by Hitachi in
high volumes, both MR and GMR, except certain dimensions are smaller.
Since this demonstration head was produced using some actual manufacturing
processes, it is likely that advanced GMR heads can be manufactured
with higher areal densities than currently available in the marketplace.
As future areal densities and internal data rates increase, it will
be necessary to evolve production from MR to the more sensitive
GMR heads. Fortunately, a majority of the manufacturing processing
and testing tools are common to both MR and GMR heads. With this
commonality, the years of experience gained manufacturing MR heads
is being directly applied to manufacturing GMR heads.
MR and GMR head processing requires photolithography to define the head structure; e.g. the features that determine the track width seen by the read head ("read track width"). The nominal MR read track width were 2/3 of the track pitch to accommodate tolerances for head width. track-to-track spacing, and track following, a 2.6 Gbits/in² (12,500 tracks/in.) HDD would require a 1.33 micron read track width. Using this estimate, the required read track widths for 10 Gbits/in² and 40 Gbits/in² is 0.68 and 0.34 microns, respectively. In addition to satisfying these read track width requirements, the photolithography must have sufficient depth of field to accurately define any non-planar head features in a merged read and write head. Fortunately, with the semiconductor industry's emphasis on higher density integrated circuits, we expect the capability of projection photolithography, with possibly a few enhancements, will be adequate to support the projected areal density growth in HDDs.
MR and GMR head manufacturing also requires precision deposition tools to control film thickness. The films used in the GMR sensor are very thin and the tolerances are tight; e.g. a copper conducting spacer is less than 15 atomic layers thick. GMR heads also contain thin film materials which require precise process control to achieve compositional uniformity.
These manufacturing challenges are being addressed now, so the transition from MR to GMR will be well underway by the year 2000. The basic GMR structure used will continue to follow the IBM-developed spin valve concept for this future progress.
Summary
GMR heads are starting to be used in HDD products, because more sensitive heads are needed to maintain high quality read-back signals, as areal densities and data rates increase. GMR technology is an evolutionary step from today's MR heads and this technology will utilize much of the design, production, and test experience associated with MR heads. GMR heads are expected to support areal densities well beyond 10 Gbits/in²; however, as areal densities continue to grow, more advanced structures beyond GMR may be required. Manufacturing challenges will continue to involve tight control of critical dimensions, film thickness and film compositions. Continued advancements in head technology are essential to maintain rapid areal density growth during the next decade, and GMR spin valve heads have been shown to have the ability to meet future areal density requirements. Truly, the era of GMR heads for magnetic storage has begun.
References
1 C. Tsang et al., "5 Gbits/in² Recording Demonstration With Conventional AMR Dual Element Heads And Thin Film Disks", IEEE Trans. Mag., vol. 33, no. 5, p. 2866, Sept. 1997.
2 M. Baibich et al., "Giant Magnetoresistance Of (001) Fe/(001) Cr Magnetic Superlattices", Phys. Rev. Lett., vol. 61, no. 21, p. 2472, Nov. 1988.
3 P. Grunberg, "Magnetic Field Sensor With Ferromagnetic Thin Layers Having Magnetically Antiparallel Polarized Components", U.S. Patent 4,949,039.
4 B. Dieny et al., "Magnetotransport Properties Of Magnetically Soft Spin-Valve Structures", J. Appl. Phys., vol. 69, no. 8, p. 4774, April 1991.
5 C. Tsang et al., "Design, Fabrication And Testing Of Spin Valve Read Heads For High Density Recording", IEEE Trans. Mag., vol. 30, no. 6, p. 3801, Nov. 1994.
6 C. Tsang et al., unpublished IBM investigation.
7 M. Williams, IBM Almaden Research Center, unpublished calculations.
© International Business Machines Corporation 1998

Question: what causes the curvature of the tvrdi disk

what causes the curvature of the tvrdi disk

Question: what is the starting point of a tvrdi disk

what is the starting point of a tvrdi disk

Question: what induced the curvature of the tvds disk

električni napon kod svake promjene polja

what induced the curvature of the tvds disk

Question: where does the magnetic field of a tvrdi disk come from

where does the magnetic field of a tvrdi disk come from

Question: what causes the head curve to change

Question: when is the beginning of a tvrdi disk read

when a series of differently magnetized areas

kada niz različito magnetiziranih područja

when a series of differently magnetized areas

when is the beginning of a tvrdi disk read

Question: how does the magnetic head curve change

The reading of the beginning was done using the fact that when a series of differently magnetized areas quickly pass under the magnetic head curve , the curve was induced by electric voltage at each field change .

This position on the disk contains: Master Partition Table, GTP, and Master Boot Code, GKP.

II. Generalities
Each hard disk has to be partitioned before any data can be stored on it. A partition is a contiguous chunk of the hard disk space and contains either, a file system, or logical volumes, as it is primary or extended. A file system is an arrangement of directories and files strictly connected with an operating systems which implements it. Internally, a logical volume resembles a primary partition. It also contains a file system, and from such point of view, primary partitions and logical volumes are indistinguishable, thus we call them all simply volumes. Logical volumes may be considered primary partitions, lined up in a chain within an extended partition, so that the first one holds the address of the second one and so on. Sometimes, logical volumes are called logical drives or logical partitions.
Note: We make strict distinction between partitions and slices. Partitions are an element of the x86 architecture, while slices are related to data storage on Unix systems.
Only four partitions per a hard disk drive are allowed. Extended partitions and logical volumes were developed to allow the use of larger hard disks with DOS, while the compatibility with previous standards is preserved. Logical volumes help also to keep data on a hard disk well organized, and to avoid the slack which appears when large clusters are used on large partitions. See [Kozierok] for further details on this topic.
Within DOS and Windows 3.x/95/98 only the first primary and the first extended partition of the hard disk are accessible. Solaris, Linux, and Windows NT can access all volumes in any combination, i.e. their fdisk programs may create and delete multiple primary and extended partitions. In DOS and Windows for all volumes, that are accessible, consecutive letters - drive letters - are assigned, starting with C. To determine the way letters are assigned following rules apply:
This schema of assignment has nothing to do with lettering in the BIOS boot sequence. When two channel EIDE controller is used then primary master drive has assigned letter C, primary slave D, secondary master E and secondary slave F.
In Windows NT drive letters to all volumes, except the boot partition, may be assigned manually. In W2K additionally volumes (file systems) may be mounted in directories.
The main difference between primary and extended partition is that only the first one is boot-able by BIOS. There are boot managers e.g. Lilo or Ranish PM that are able to boot from logical volume. Obviously, operating system files may be stored on primary as well on extended partition. Usually, only a few files which are used in the early phase of the boot process must reside on the boot primary partition.
There are many file systems, but the most commonly used are: FAT-16, FAT-32 implemented in Service Release 2 of Windows 95, NTFS implemented by Windows NT 4.0, UFS used by Solaris, and HPFS used by OS/2. FAT-16 is recognized and fully supported by most operating systems available on PC platform. FAT-16 volume is a good solution for data exchange between operating systems running on the same machine. FAT-16 and FAT-32 are not compatible. NT 4.0 does not recognize FAT-32 without additional software while W2K fully supports it.
Note: NTFS version 3 used by NT 4.0 is not compatible with NTFS version 5 introduced in Service Pack 4 for NT 4.0 and used by W2K. All NTFS volumes version 3 are automatically converted to version 5 when used under W2K. The operation can not be reversed, which makes them unusable in NT 4.0.
Solaris UFS file system has been improved in Solaris 7 by acquisition of
journal file system methods, which can save headaches with data restoration
after the system crash or unattended power failure. The new feature is called
"logging" and can be turned on when a file system is mounted. On the command
line it is done by supplying
-o logging file system
specific option to
mount command (see
mount,
mount_ufs man pages).
To mount default file systems during boot process
logging should
be added to mount option field in
/etc/vfstab configuration file
(see vfstab man page).
The first sector of a hard disk drive is called its Master Boot Record or briefly MBR. Its coordinates are Cylinder 0, Head 0, Sector 1. It stores two sorts of information: Master Partition Table and Master Boot Code. Master Partition Table, also known as fdisk table, contains the descriptions of the partitions on the hard disk. Since MBR must fit into 512 bytes there is only room for four partitions. Therefore, a hard disk can have up to four partitions.
Note: Windows NT and W2K store the information on drive letter assignment in NT Disk Signature, which is unique for every hard disk drive. This signature is simply 4 bytes of MBR starting at byte 0x1B8 - right before the definition of partition number 1. Most of boot managers and partition managers do not preserve this bit of data, which may lead to troubles in case of non-standard drive lettering.
Each partition entry in the Master Partition Table has its Partition ID, Activity Flag, Start Cylinder/Head/Sector, and End Cylinder/Head/Sector specified.
The Partition ID specifies the type of the partition (or to what OS it belongs), Activity Flag determines which primary partition should be booted, and the Start/End specify location of the partition [Richmond]. The following Partition IDs are mostly used:
If there is an extended partition on the disk, Master Partition Table holds a link to an Extended Partition Table that describes the first logical volume for the partition. That table contains information about that first logical volume, and a link to the next Extended Partition Table which describes the second logical volume on that partition, and so on. This allows for infinite number of logical volumes, theoretically.
To load an operating system, BIOS as a starting point of the boot process, needs to know where that operating system resides. Instead, BIOS loads Master Boot Code - small initial boot program in the MBR. This program eventually transfers control to the partition boot program stored at the first sector of the active partition.
Each volume - primary partition or logical volume - has its own Volume Boot Sector. This is distinct from the MBR that controls the entire disk, but is similar in concept. Each VBS contains Disk Parameter Block and Volume Boot Code. Disk Parameter Block, sometimes called the media parameter block, is a data table that contains specific information about the volume, such as its size, number of sectors it contains, label name etc. Volume Boot Code is a code that is specific to an operating system that is using this volume and is used to start the load of the operating system.
The Volume Boot Sector is created during a high-level format of a hard disk partition. On floppy disks, the first physical sector is VBS.
Solaris Volume Boot Sector is called Partition Boot Record, or shortly PBR.
The boot process, also known as bootstrapping, on PC begins when the computer is turned on (cold start), or after the reset (warm start). First, the system firmware in the BIOS ROM executes a power-on self test (POST), a kind of hardware check, and runs BIOS extensions in peripheral board ROMs. After devices are configured, BIOS invokes software interrupt Int 19h. The Int 19h handler typically loads the first physical sector of the boot disk into memory locations 0x0000:0x7C00 through 0x0000:0x7DFF and then passes control to the boot code placed in that sector. Which disk is the boot one depends on the BIOS boot sequence setting. When SCSI is selected, then suitable setting in the SCSI host adapter's BIOS ROM determines the boot drive. Newer BIOSes allow to boot from CD-ROM, LAN or some removable media like ZIP or LS-120.
On a hard disk, the first physical sector is its MBR, and the boot code is the Master Boot Code. First, MBR moves itself to 0x0000:0x0600, then loads the VBS of the first active primary partition on the boot disk to it's original location 0x0000:0x7C00, and jumps to its first byte, unless a non-standard Master Boot Code is in use, such as Lilo or Ranish PM. This completes the standard PC hard disk sequence.
For a floppy disk, the first physical sector is the VBS. The BIOS does not care whether it is loading an MBR or a VBS. When booting from a floppy disk, which has no partitioning information and therefore no MBR, only the VBS is effectively loaded (cf. [Locke]).
After the BIOS passed control to either, MBR in case of booting from a hard disk, or VBS when booting from a floppy, the boot program specific to the operating system is started. Its behavior depends strictly on the operating system. Generally, the rest of the boot process, as well as its initial part, is divided into more and more advanced boot stages. Some operating systems like Solaris, Linux, or NT allow for user interaction during the system load. All these systems offer their own boot managers, i.e. programs which give user some control over the boot process, and thus make coexistence of many operating systems on one machine easier. A boot manager need not to be the part of an operating system. There are many third party boot managers, from tiny OS-BS, to very powerful, though complex, System Commander.
DOS and Windows 3.x/9x boot process is simplified. There is no user interaction.
Volume Boot Code simply loads
io.sys file, which then loads device
drivers and starts user shell.
Modern operating systems are not limited to boot off the local hard disk drive only. Solaris and NT are capable to boot across the network. This makes possible to have fully functional workstations with no hard disk drives, which reduces costs of management and administration.

Question: where is the master partition table located on a tvrdi

Master boot record (MBR) of 512 bytes, otherwise the first sector on the disk on the physical location: cylinder=0, head=0, sector=1.

This position on the disk contains: Master Partition Table, GTP, and Master Boot Code, GKP.

where is the master partition table located on a tvrdi

Question: what is the master boot code on a tvrdi disk

what is the master boot code on a tvrdi disk

Question: how many bytes are in a master boot record

512 bajtova , inače prvi sektor na disku na fizičkoj

how many bytes are in a master boot record

Question: what is the name of the master partition table on a tvrdi disk

Master Partition Table ( glavnu tablicu podijela na disku ) GTP i Master Boot Code ( glavni kod za pokretanje

what is the name of the master partition table on a tvrdi disk

Question: what is the first sector on a tvrdi disk

what is the first sector on a tvrdi disk

Question: where is master partition table located on a disk

where is master partition table located on a disk

Question: where is the master boot record located on a disk

the first sector on the disk on the physical location

prvi sektor na disku na fizičkoj lokaciji

the first sector on the disk on the physical location

where is the master boot record located on a disk

Master boot record ( MBR ) of 512 bytes , otherwise the first sector on the disk on the physical location : cylinder=0 , head=0 , sector=1 .

This position on the disk contains : Master Partition Table , GTP , and Master Boot Code , GKP .

Master boot record (MBR) veličine 512 bajtova, inače prvi sektor na disku na fizičkoj lokaciji: cilindar=0, glava=0, sektor=1.

Master boot record (MBR) of 512 bytes, otherwise the first sector on the disk on the physical location: cylinder=0, head=0, sector=1. This position on the disk contains: Master Partition Table, GTP, and Master Boot Code, GKP.

Master boot record (MBR) of 512 bytes, otherwise the first sector on the disk on the physical location: cylinder=0, head=0, sector=1.

This position on the disk contains: Master Partition Table, GTP, and Master Boot Code, GKP.

1980 - the first disk capacity of 1 GB, IBM 3380, the size of the refrigerator, weighing about 250 kg, and the price of $40,000.

Hitachi Global Storage Technologies is first to the mat with an announcement of a 1-terabyte hard disk drive. Industry analysts widely expected a 1TB drive to ship sometime in 2007; Hitachi grabbed a head start on the competition by announcing its drive today, just before the largest U.S. consumer electronics show starts next week.
According to Hitachi, the drive ships in the first quarter of 2007, and will cost $399--less than the price of two individual 500GB hard drives today. The drive, called the Deskstar 7K1000, will be shown this weekend in Las Vegas at the 2007 International CES, also known as the Consumer Electronics Show, as well as at the Storage Visions storage conference.
Hitachi will have three flavors of the 1TB drive; however, only the Deskstar version will be available at launch. The company also plans to offer a CinemaStar version of the drive, for use in DVR and set-top boxes, as well as an enterprise version with a certified mean time between failure rating. Both of those versions are expected in the second quarter of this year.
"No question, it's a milestone for the industry," says John Rydning, research manager for hard disk drives and components at IDC. "It's interesting that the industry is delivering a 1TB drive in the 51st year of the industry." The first hard drive, manufactured by IBM, shipped in 1956.
Hitachi notes it took the industry 35 years to reach 1GB (in 1991), 14 years more to reach 500GB (in 2005), and just two more years to reach 1TB.
The company hopes to be the first to market with a 1TB drive. The company is locked in competition with Seagate for those honors; Seagate reconfirmed its intentions to ship a 1TB drive in the first half of 2007, but it has not offered any further details.
Although the jump to 1TB was not unexpected, Hitachi is taking a cautious tactic to achieving 1TB. According to Doug Pickford, director of market and product strategy, "The approach we've taken with the design of this product, and with previous generation products, is that we've purposely relaxed the areal density. The previous generation [500GB] drive was 100GB per platter; and, it was possible to have up to 160GB per platter. About 250GB per platter is the next bump on the areal density curve, but we've backed off from doing that in order to achieve higher reliability at this time."
The Deskstar 7K1000 will be a five-platter drive, each platter capable of storing 200GB apiece. Like Seagate's Barracuda 7200.10 750GB drive, Hitachi's 1TB model uses perpendicular magnetic recording (PMR) to achieve its high capacity point. The 7K1000 is Hitachi's first 3.5-inch hard drive to use PMR technology; last year, the company released 2.5-inch PMR-based hard drives.
Pickford says the drive will be intended for gaming and high-performance PCs, external storage devices, and PC upgrades. "The drive will be shipping in the first quarter to retail stores," says Pickford. "And we're expecting to ship some to external storage device makers as well."
The 7200 rpm Serial-ATA drive will have 32MB data buffer, larger than the typical 8MB or 16MB buffer seen on drives. It will be available in SATA 3.0Gb/s and Parallel-ATA 133 interfaces.
In addition to the 1TB model, Hitachi is introducing and shipping a 750GB version of the drive as well. But the company focused its energies on achieving 1TB before its competitors. "We did that by design," says Pickford. "The feedback we got from the market was that if we could get to 1TB sooner, there would be a lot of value for our customers. We already knew that the mechanical platform was mature enough and able to handle the areal density that 1TB needed. So we decided to accelerate our efforts and get to a TB."
Getting to 1TB, adds Pickford, was more about finessing existing processes than inventing new ones. "It was very much in the execution, so you can have the right yields, the right stability, and right quality levels, and make sure it's achievable in the lab as well as in mass production."
With a price of $399, the Deskstar 7K1000 comes in at an attractive price for consumers. That works out to $0.40 per GB--a competitive per-gigabyte cost for a hard drive today, and not much of a premium over previous models. By comparison, a 500GB hard drive today costs about $0.45 per gigabyte, as does Seagate's 750GB Barracuda drive (down from the $0.79 per gigabyte it cost when it launched last spring).
Don't expect to see hard drive prices enter a freefall, though. Says Pickford, "I don't think it will affect the market in a disruptive way. When we set this, we did try to take into account the price of other, lower-capacity drive products. Based on where the market was, we felt $399 was an appropriate price point to set for this technology, so it could achieve good market acceptance."
Although 1TB of storage on a single drive will be alluring to some users, IDC's Rydning sees only very specific demand for that much storage. "For consumers, we still think the big hard drives are mainly for niche applications," says Rydning. "There's going to be a certain minority of PC users and video recorder enthusiasts who will want to have the highest capacity available. And in those markets, a high-capacity drive is valued. However, the vast majority of PC users are still serviced by a one-platter, 160GB hard drive."
Consumers' increasing accumulation of digital personal data is, not surprisingly, driving the need for high-capacity storage. "As people amass their own personal memories, either in photographs or video, hard disk drive storage is one of the best, lowest cost ways to store and retrieve that type of data," says Rydning.

Question: what was the price of the first tvrdi disk

1980 - the first disk capacity of 1 GB, IBM 3380, the size of the refrigerator, weighing about 250 kg, and the price of $40,000.

what was the price of the first tvrdi disk

Question: what was the first disk capacity of a tvrdi

what was the first disk capacity of a tvrdi

Question: when did the first tvrdi come out

Question: what is the weight of a tvrdi refrigerator

what is the weight of a tvrdi refrigerator

Question: what is the capacity of a tvrdi disk

Question: what was the size of the refrigerator in 1980

what was the size of the refrigerator in 1980

1980 - the first disk capacity of 1 GB , IBM 3380 , the size of the refrigerator , weighing about 250 kg , and the price of $ 40,000 .

1986 - standardization of SCSI 1998 - standardization of access UltraDMA/33 and ATAPI 2002 - addressing over 137 GB of disk space 2003 . - introduction of the SATA standard 2005 . - first hard disk capacity 500 GB ( Hitachi ) 2005 . - standardization of Serial ATA 3 G 2005 . - introduction of the SAS standard ( Serial Attached SCSI ) 2005 . - Toshiba introduced smart recording 2006 . - first disk capacity 750 GB ( Seagate ) 2007 . - first disk capacity 1000 GB ( 1 TB - terabyte ) Hitachi 2008 . - first disk capacity 1.5 TB ( Seagate ) 2009 . - first disk capacity 2 TB ( Western Digital ) 2010 . - first disk capacity 3 TB ( Seagate )

1980. - prvi disk kapaciteta 1 GB, IBM 3380, veličine hladnjaka, težak oko 250 kg, i cijene 40.000 USD.

1980 - the first disk capacity of 1 GB, IBM 3380, the size of the refrigerator, weighing about 250 kg, and the price of $40,000. 1986 - standardization of SCSI 1998 - standardization of access UltraDMA/33 and ATAPI 2002 - addressing over 137 GB of disk space 2003. - introduction of the SATA standard 2005. - first hard disk capacity 500 GB (Hitachi) 2005. - standardization of Serial ATA 3G 2005. - introduction of the SAS standard (Serial Attached SCSI) 2005. - Toshiba introduced smart recording 2006. - first disk capacity 750 GB (Seagate) 2007. - first disk capacity 1000 GB (1 TB - terabyte) Hitachi 2008. - first disk capacity 1.5 TB (Seagate) 2009. - first disk capacity 2 TB (Western Digital) 2010. - first disk capacity 3 TB (Seagate)

1980 - the first disk capacity of 1 GB, IBM 3380, the size of the refrigerator, weighing about 250 kg, and the price of $40,000.

The transfer of many today’s hard drives (2015), approaching 1 TB per square col, Bruno Marchon, Thomas Pitchford, Yiao-Tee Hsia, and Sunita Gangopadhyay2The Head-Disk Interface Roadmap to an Areal Density of Tbit/in2, Advances in Tribology Volume 2013 (2013), Article ID 521086, 8 pages, accessed: June 2, 2015 and the development of various technologies for magnetic heads, and new data recording technologies, and filling the interior with inert gases and some other innovations will enable recording density and up to 4 TB per square col of magnetic medium.

Tribology of the Head-Disk InterfaceView this Special Issue
The Head-Disk Interface Roadmap to an Areal Density of Tbit/in2
Abstract
This paper reviews the state of the head-disk interface (HDI) technology, and more particularly the head-medium spacing (HMS), for today’s and future hard-disk drives. Current storage areal density on a disk surface is fast approaching the one terabit per square inch mark, although the compound annual growth rate has reduced considerably from ~100%/annum in the late 1990s to 20–30% today. This rate is now lower than the historical, Moore’s law equivalent of ~40%/annum. A necessary enabler to a high areal density is the HMS, or the distance from the bottom of the read sensor on the flying head to the top of the magnetic medium on the rotating disk. This paper describes the various components of the HMS and various scenarios and challenges on how to achieve a goal of 4.0–4.5 nm for the 4 Tbit/in2 density point. Special considerations will also be given to the implication of disruptive technologies such as sealing the drive in an inert atmosphere and novel recording schemes such as bit patterned media and heat assisted magnetic recording.
1. Introduction
As the areal density of commercial hard disk drives is quickly approaching the terabit per square inch milestone [1–5] (Figure 1), the need to improve the reliability of the head-disk interface (HDI) and to further decrease the head-medium spacing (HMS) is becoming eversmore critical [3, 6, 7]. Low HMS is a necessary enabler to good writability as well as strong read-back signal integrity [8, 9]. It is estimated that the HMS will soon need to cross the 7 nm mark in order to reach this terabit per square inch density point [2, 6]. It is remarkable to realize that the error rate of the stored digital signal that is being read back improves approximately by about 2x for every 0.3–0.5 nanometer of decreased HMS. In addition to relentless demand for novel, ultrathin protecting films of overcoat and lubricant, and subnanometer air gap between the disk and the head, alternative recording technologies presently being contemplated involve heating the disk to over 500°C (heat-assisted magnetic recording or HAMR) [10–12] and/or physically isolating magnetic bits on small islands of sub-30 nm in physical dimensions (bit-patterned recording or BPR) [13–16].
In this paper, the roadmap to an areal density of 4 terabits per square inches will be discussed. Particular emphasis will be given to the various spacing components that comprise the HMS budgetand their physical limits. The various implications of recording technologies incorporating HAMR and/or BPR will also be addressed.
2. Historical Perspective
Hard drive technology has constantly evolved to achieve consistent areal density growth. As one technology such as longitudinal recording has reached its limit, another such as perpendicular recording has taken over [18]. Along with advances in heads, media, signal processing, and servo technology, areal density growth is sustained through improvements in the head-disk interface (HDI). Head-media spacing (HMS) is the most important HDI parameter related to areal density growth [6]. Continued developments in the tribological design of disk drives have maintained the reliability of the head/disk interface despite decreased spacing.
Analysis of long-term trends shows that HMS has steadily declined over time (Figure 2). The historical trends indicate that the HMS of recent products is ~60% of bit length (Figure 3) [6]. The HMS for recording demonstrations has been typically more aggressive, at ~50% of bit length.
Research consortia such as the Information Storage Industry Consortium (INSIC—www.insic.com/), Storage Research Consortium (SRC—http://www.srcjp.gr.jp/), and the Advanced Storage Technology Consortium (ASTC—http://www.idema.org/?page_id=3193) have included collaborations on HDI technology development. For each areal density, the HMS target has typically been set by the Recording Subsystem (RSS) groups. The past and current HMS trends for the different consortia are shown in Figure 4. The HMS trends have typically followed the overall trends of Figures 2 and 3 fairly well. For the HMS roadmaps released in 2003–2010, the INSIC trend tended to be lower than for SRC. For the current update (2012), the ASTC trend is higher than SRC.
For ASTC the main areal density targets are 2 Tb/in² and 4 Tb/in², with scheduled product introductions of 2016 and 2020, respectively. The current HMS targets for these two density points is ~5-6 and 4-5 nm, respectively, that is, less aggressive than those for INSIC. The 4 Tb/in2 HMS goal will be discussed in more details in Section 4.
3. Definition of the Head-Media Spacing Components
As the capacity and performance of disk drives has improved, the mechanical interface has evolved. The spacing between the head and the media has steadily decreased to achieve the rapid improvements in areal density. Figure 5 is a diagram of head-media spacing (HMS). The HMS is comprised of the fly height and coatings (head and disk overcoats, disk lubricant).
(a)
(b)
In the diagram of Figure 5(b), the surfaces are assumed to be perfectly smooth—they do not include factors such as surface topography and variability of the fly height. The fly height denotes the spacing between the centerline surfaces of the head and disk. The clearance denotes the spacing between the close points of the surfaces. The distinction between fly height and clearance is depicted in Figure 6.
Below are some definitions of terms commonly used by the HDI/tribology community.(1) Head-media spacing (HMS): the spacing between the top of the magnetic layer and the surface of the transducer. (2) Flying clearance: difference or margin in fly height between nominal operation and contact between the head and disk.(3) Glide avalanche/touchdown height (TDH): the lowest slider flying height above the mean roughness level without significant slider-disk contact(4) Flying height = flying clearance + touchdown height (5) Media lubricant thickness: the average thickness of the lubricant, assumed to be on top of the media overcoat(6) Media cvercoat thickness: the average thickness of the media overcoat, assumed to follow the topography of the underlying surface(7) Head overcoat: head adhesion layer (e.g., silicon) + diamond-like carbon (DLC)
For current hard drives, HMS reductions have been achieved mostly through reductions in the clearance and disk and head overcoats. While this trend will continue for the immediate future, additional HMS reductions will soon require notraditional HDI designs in order to meet the demanding recording requirements for areal densities beyond 1 Tb/in².
In older drive designs, the air bearing design and passive topography of the slider determined the fly height and clearance of the transducer. In newer drive designs, the fly height is actively controlled by a signal that changes the shape of the slider. The most common method used for this control is to embed an electrical resistive heater in the slider that will cause the transducer area to protrude closer to the disk, as is shown in Figure 6 [19–21]. At some point the interface may need to be designed to withstand intermittent or continuous contact [22–27].
Current products have HMS on the order of 10 nm or slightly below [6]. For the 1 Tb/in² products under development, a Hi-Lo range bracket can be defined, since this areal density point is no longer precompetitive. For beyond 1 Tb/in², achievable and stretch values were estimated. The technological development required to achieve the targets will be discussed in Section 4. The assessment indicated that there is promise for achieving 4–6 nm HMS in the long term. While advancements in HDI design could enable significant reduction in HMS, new recording schemes could add to the challenge due to new sources of HMS loss: heat assisted magnetic recording (HAMR) will experience effects of high temperature at the interface [28–30], and bit-patterned magnetic recording (BPR) could have issues with added disk topography that would add to the touchdown height [31–34].
4. ASTC HDI Roadmap to Tb/ and Major Research Challenges
As shown in Figure 2, a good estimation of the HMS is ~60% of the length of the bit, and some rationale for this was recently proposed [6]. This offers a convenient way to project future HMS values, as the following simple equations can be derived. If one defines areal density (AD) in bits per square inch as the product of the linear density in bit per inch (BPI) and track density (TPI), AD = BPI · TPI. Furthermore, the bit aspect ratio BAR is usually defined as BAR = BPI/TPI; hence, the bit length (BL), in inches, can be expressed as With the HMS approximation of 60% of BL, we now have a very convenient expression linking HMS (in nanometer) to AD (in Tb/in2), for a given BAR: Numerical HMS values based on (3) are reproduced in Table 1 below.
As shown in Table 1, achieving a 4 Tb/in2 areal density will require an HMS in the vicinity of ~4.4 nm, assuming a bit aspect ratio (BAR) of 3. Table 2 offers two scenarios for the HMS breakdown into its various components. In the table, the 2010 projection from INSIC is also presented, as well as a realistic range for the 1 Tb/in2 density point that sponsor companies are working towards. For the 4 Tb/in2 point, both “Achievable” and “Stretch” values are offered, corresponding to roughly 60–100% and <60% chance of success, respectively. It is clear from the table that achieving the ~4.4 nm goal is a high risk, and it will require evolutionary as well as revolutionary changes in materials, processes, and clearance control schemes. HDD architecture (e.g., sealing in inert atmosphere) might also be needed [35]. This is discussed in the following sections.
4.1. Materials: Disk and Head Overcoat
It is clear from Table 2 that the biggest contributor to today’s HMS is the carbon overcoat, both on the disk and on the head. Combined, they amount to about half of today’s (aka 1 Tb/in2) HMS budget. Historically, overcoat thickness reduction on both components has been enabled by denser carbon, as well as smoother underlying surfaces for the magnetic medium (disk) and RW elements (head). Head carbon has evolved from sputtered to plasma-enhanced chemical vapor deposition (PE-CVD) to filtered cathodic arc (f-CAC) carbon [36–39], which increased the density, sp3/sp2 ratio, and hardness [40]. On the disk side, f-CAC technology has not yet been made manufacturable [41, 42], mostly because of particle and deposition rate challenges, and most if not all disks shipped today are coated with some sort of PE-CVD deposited amorphous carbon overcoat. It is believed that disk deposition tools will soon need to offer new carbon technologies, able to closely emulate a high sp3 bonded, f-CAC-type carbon film. On the head side, evolutionary optimization of the overcoat technology might allow to reach the 4 Tb/in2 goal of ~1 nm, believed to be the ultimate coverage limit of f-CAC. Finally, although many attempts have been made by disk manufacturers to develop and ship noncarbon overcoated disks, it remains an open question whether any thin film materials other than carbon can be made as hard, dense, and chemically inert as carbon films [43–47]. The latter issue could be alleviated if HDD’s can be sealed in an inert environment [35]. It is also believed that such a drastic change in the drive mechanical platform could help reduce overcoat thickness on both heads and disks, as magnetic medium and read/write alloy corrosion could then be suppressed, or at least drastically reduced. Our estimate of such benefit is in the range of 0.2–0.3 nm or greater, for an overall reduction of ~0.5 nm, that is, a substantial amount of about 10% of the total HMS. Another potential alternative is to develop a disk surface modification process such that the highly corrosion-susceptible media material surface is treated or modified without contributing to spacing loss with a creation of a nonfunctional or weakened layer of magnetic material on the media surface [48, 49].
4.2. Materials: Disk Lubricant
Table 2 shows that a 0.2 nm reduction of lubricant thickness from 1.0–1.2 to 0.8–1.0 is needed. This does not seem like much, but with today’s extremely tight reliability/HMS margins, this change is actually significant, and it is believed that inventions will be needed to reach those goals [50, 51]. The lubricant industry is now more diversified than before, and new lubricant structures are now routinely offered by at least three different companies. It remains to be seen whether conventional lubricant chemistries (functionalized perfluoropolyether) will be able to achieve this thickness goal. Perhaps unconventional approaches, such as direct surface treatment/functionalization of the disk overcoat will be needed [48].
4.3. TDH: Topography
Touchdown height (TDH) globally defines all residual disk and head topographies that prevent the head from coming into close proximity to the magnetic medium (Figure 6). It is affected by waviness (~1–1000 μm wavelength range) and roughness (<1 μm) of the substrate [52–54], as well as the nanoroughness of the magnetic film-overcoat structure of the disk [55]. Unlike materials thicknesses (lubricant, overcoat), TDH is not a requirement for proper HDD reliability and could, in theory, be brought to zero. It assumed that engineering evolutionary optimization of polishing (disk substrate, slider) and deposition (media/overcoat) processes will be possible to achieve the HMS goal. Finally, it has been proposed that disk lubricant “roughness”, both at the nanoscale (conformation) [56] and the microscale (thickness modulation or “moguls” [57] and “ripples” [58, 59]), also contributes to TDH, and lubricant optimization, as discussed previously, will be needed to also lower its contribution.
4.4. Head-Disk Clearance
Of all the HMS contributors, clearance has probably exhibited the largest decrease in the last 10 years or so, thanks to the advent of thermal flying height control (TFC-Figure 7) [19, 21]. This revolutionary approach has allowed the HDD industry to achieve a 10-fold reduction in clearance from ca. 10 nm ten years ago to ~1.5 nm today (Table 2). To achieve the 0.6 nm ASTC clearance goal and to easily compensate for clearance changes induced by temperature, altitude, or humidity, further enhancement of clearance control will be needed such as closed-loop TFC control. “Surfing” of light contact recording has also been suggested [26], but it remains to be seen whether this approach can be made reliable.
5. Tribology and HDI Challenges for Alternate Technologies
As discussed earlier, to advance HDD magnetic recording beyond the ~1 Tb/in² believed achievable with PMR/SMR, HAMR and BPM technologies are being developed. It is believed that HAMR will first be introduced. To go beyond ~6 Tb/in², the ASTC roadmap shows that HAMR will be augmented with BPM recording technology [11]. While these will enable significant gains in areal density, they will present challenges for the HDI.
In terms of HMS, the effect of these technologies is shown in the “HMS Adder” columns of Table 2. The touchdown height is increased due to added media roughness for HAMR or residual topography for BPM [32, 60]. The increased roughness also drives the need for added media overcoat thickness to maintain adequate coverage. With regards to clearance, HAMR would require added margin as a guardband for possible thermal protrusion of the near-field transducer (NFT) [10], whereas BPM will require clearance margin as a guardband against residual topography that could induce head wear. It is believed that BPM will not require head overcoat thickness adder.
As the HDD industry moves towards the introduction of HAMR recording technologies, there is a high demand for the HDI to demonstrate robustness at higher temperatures [30, 61–63]. If the current disk overcoat and lubricant films are not capable of withstanding the high recording temperature (>500°C), new materials will be needed. On the head side, it is currently believed that the temperature should be limited to ~150°C in order to provide long-term interface reliability to the current overcoat material. In any event, further development in tribological materials for both heads and media seem likely needed in order to insure proper reliability of the HAMR interface.
The later introduction of BPM recording technology will present further challenges for HDI design. Residual topography left behind by the BPM manufacturing process challenges air bearing designers to design a slider that can better follow residual topography [34, 64, 65] as well as media manufacturers to have a uniform overcoat and lubricant coverage of the media surface. Moreover, the residual media topography could lead to excessive induced lubricant roughness on the microscale (lubricant moguls and ripples) unless a new lubricant can be designed.
6. Conclusion
In summary, head-media spacing continues to be an enabler for continued march to increase the areal density to fend off the assault and encroachment by nonvolatile solid-state memory technologies. To maintain HDD leadership and competitive edge in the data storage arena, the industry must continue to develop new component technologies to support this areal density advance. However, to be successful, the design of the head-disk interface must be an integrated effort where the component technologies are developed in concert to solve the system problem. The success of the areal density growth will depend on how successful we, as an industry, are in integrating this development.
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1 TB po kvadratnom colu , Bruno Marchon , Thomas Pitchford , Yiao - Tee Hsia , i Sunita Gangopadhyay2The Head - Disk Interface Roadmap to an Areal Density of Tbit / in2 , Advances in Tribology Volume 2013 ( 2013 ) , Article ID 521086 , 8 pages , pristupljeno : 2 . lipnja 2015 . a razvojem raznih tehnologija za magnetske glave , te novih tehnologija za zapisivanje podataka , te ispunjavanja unutrašnjosti inertnim plinovima i još nekim drugim inovacijama omogućit će gustoće zapisivanja i do 4 TB po kvadratnom colu magnetskog medija .

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The transfer of many today ’s hard drives ( 2015 ) , approaching 1 TB per square col , Bruno Marchon , Thomas Pitchford , Yiao - Tee Hsia , and Sunita Gangopadhyay2The Head - Disk Interface Roadmap to an Areal Density of Tbit / in2 , Advances in Tribology Volume 2013 ( 2013 ) , Article ID 521086 , 8 pages , accessed : June 2 , 2015 and the development of various technologies for magnetic heads , and new data recording technologies , and filling the interior with inert gases and some other innovations will enable recording density and up to 4 TB per square col of magnetic medium .

Zapremina mnogih današnih tvrdih diskova (2015.) približavaju se 1 TB po kvadratnom colu, Bruno Marchon, Thomas Pitchford, Yiao-Tee Hsia, i Sunita Gangopadhyay2The Head-Disk Interface Roadmap to an Areal Density of Tbit/in2, Advances in Tribology Volume 2013 (2013), Article ID 521086, 8 pages, pristupljeno: 2. lipnja 2015. a razvojem raznih tehnologija za magnetske glave, te novih tehnologija za zapisivanje podataka, te ispunjavanja unutrašnjosti inertnim plinovima i još nekim drugim inovacijama omogućit će gustoće zapisivanja i do 4 TB po kvadratnom colu magnetskog medija.

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Those 7mm-thick hard drives you've seen in some Ultrabooks are already looking a tad on the chunky side. Western Digital has started producing sample versions of a hybrid hard drive (you're not yet looking at it here) that measures just 5mm (0.2in) tall, even as it crams in both flash and a 500GB main disk. If you think the slimmer drive is just the ticket for a best-of-all-worlds laptop that's both fast and capacious, you're not alone: Acer and ASUS have mentioned their collaboration in the same breath, which may be a strong clue as to where future Aspires and Zenbooks are going. The remaining question is when they arrive. Sampling isn't the same as mass production, which could leave us with months to go before the 5mm drive lands in future extra-skinny PCs.
WD® Creates World's Thinnest 2.5-inch Hybrid Hard Drive
New 5 mm Standard Slashes Storage Footprint by Almost 50% Compared to Traditional 2.5-inch Hard Drives
IRVINE, Calif. – Sept. 10, 2012 – WD®, a subsidiary of Western Digital Corp. (NASDAQ: WDC) today announced it is sampling a 5mm-thin hard disk drive featuring hybrid technology. WD has developed hard drives slim enough for integration into today's thinnest notebook PCs, which provide high-capacity storage and robustness while featuring instant-on and application performance similar to today's client solid state drives (SSDs). The new technologies will be showcased during WD's Investor Day, Sept. 13, 2012.
"Mobile devices are becoming smaller, thinner, lighter and more responsive," said Matt Rutledge, vice president of client storage solutions at WD. "Working with our technology partners, WD has developed new 5 mm hard drives that enable high capacity storage along with excellent performance and superior economics to allow our customers to expand their thin offerings."
With device volumetric efficiency a key concern for system makers, WD began shipping 7 mm height hard drives for thin-profile notebooks earlier this year (historically, standard notebook hard drives have been 9.5 mm). WD 5 mm hybrid hard drives will enable the market's thinnest computers to offer 500 GB of capacity, utilizing almost 50% less volume compared to current 9.5 mm hard drives and at one tenth the cost of similar capacity SSDs.
"Acer is partnering with WD to bring advanced notebook performance and capacity in the smallest form factor," said David Lee, associate vice president of Mobile Computing Product business unit at Acer. "It's a part of our ongoing commitment to present leading technology that ultimately improves the total user experience of our customers."
"We are seeing a shift in the computing world to more powerful mobile computing solutions," said SY Shain, senior vice president of ASUS' notebook business unit. "With this in mind, ASUS and WD are collaborating to create slimmer and more mobile notebook solutions - without sacrificing capacity or performance - to deliver smaller form-factor to consumers."
Hybrid Technology and Client Tiered Storage
WD's innovative hybrid technology pairs MLC NAND flash storage for fast SSD-like data throughput and instant-on responsiveness with magnetic disks for efficient, high-capacity storage. Similar to the practice of multi-million dollar enterprise systems, WD's hybrid technology utilizes the concept of tiered storage. Data accessed most frequently (often referred to as 'hot' data) is managed using speedy NAND flash to ensure fast response times, while data accessed less often ('cold' data) resides on the robust magnetic disks. The tiered design of hybrid hard drives, compared to current dual-drive solutions, also provides a redundancy benefit for users. The magnetic disk backs up all files residing in the NAND, protecting the user from inevitable NAND wear and preserving it for the more hot data handling. WD's hybrid technology works in conjunction with the PC operating system to deliver higher performance than current hybrid offerings while minimizing NAND wear to allow the use of less expensive MLC NAND.
Hybrid hard drives combine NAND flash and magnetic disks, simplifying storage-element integration for OEM customers and providing a host of end user benefits: superior performance, responsiveness, lower power consumption, greater operating shock tolerance, and data protection. And unlike dual-drive designs, WD's hybrid technology provides single-unit design homogeneity that OEM system manufacturers have long sought from the storage industry.

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Native| Translation ------+-----+-----+----- Form 2.5"/SUPERSLIMLINE Cylinders 870| | | Capacity form/unform 42/ MB Heads 2| | | Seek time / track 19.0/ 5.0 ms Sector/track | | | Controller SCSI1 SINGLE-ENDED Precompensation Cache/Buffer 8 KB LOOK-AHEAD Landing Zone Data transfer rate 2.250 MB/S int Bytes/Sector 512 4.000 MB/S ext SYNC Recording method RLL 1/7 operating | non-operating -------------+-------------- Supply voltage 5 V Temperature *C 5 55 | -40 70 Power: sleep 0.2 W Humidity % 8 85 | 5 95 standby 0.2 W Altitude km -0.060 3.000| -0.060 12.000 idle 1.7 W Shock g 10 | 100 seek 2.2 W Rotation RPM 3600 read/write 2.0 W Acoustic dBA 40 spin-up 4.5 W ECC Bit 112,REED SOLOMON MTBF h 80000 Warranty Month Lift/Lock/Park YES Certificates CSA,FCC,IEC950,TUV,UL1950,VDE ********************************************************************** L A Y O U T ********************************************************************** QUANTUM GODRIVE 40/80S PRELIMINARY PRODUCT MANUAL REV. 0.5, 7/24/91 +--------------------------------------------------+ | | | | +--------------------------J1----------------J2----+ |+------------------------------------------------+| ||o o o o o o o o o o o . o o o o o o o 1 o o o 1|| ||o o o o o o o o o o o o o o o o o o o 2 o o o o|| |40-----------------------------------------------+| +-----------SCSI-----------------------------------+ + + J1 and J2 are fabricated from one 50-pin connector. J1 has 40 pins, J2 has 8 pins, and 2 pins have been removed at the boundry between J2 and J1. ********************************************************************** J U M P E R S ********************************************************************** QUANTUM GODRIVE 40/80S PRELIMINARY PRODUCT MANUAL REV. 0.5, 7/24/91 Jumper Setting ============== x = Factory default The GoDrive 40/80S has a single 2 x 25 connector on 2mm centers for power, data and SCSI device address. The connector also includes four pins (2x2) which are reserved as factory test points (Pins 1-4 of J2). J1 Pins 1 and 2 = +5V (Logic), Pins 3 and 4 = Logic Return. J2 SCSI ID ----------- +----------+-----------------------+ | SCSI ID | Pin | | | 5 | 6 | 7 | +----------+-------+-------+-------+ | 0 | HI | HI | HI | +----------+-------+-------+-------+ | 1 | LO | HI | HI | +----------+-------+-------+-------+ | 2 | HI | LO | HI | +----------+-------+-------+-------+ | 3 | LO | LO | HI | +----------+-------+-------+-------+ | 4 | HI | HI | LO | +----------+-------+-------+-------+ | 5 | LO | HI | LO | +----------+-------+-------+-------+ | 6 | HI | LO | LO | +----------+-------+-------+-------+ | 7 | LO | LO | LO | +----------+-------+-------+-------+ Pin 8 of J2 can be used to drive an LED during periods of drive activity. ********************************************************************** I N S T A L L ********************************************************************** QUANTUM GODRIVE 40/80S PRELIMINARY PRODUCT MANUAL REV. 0.5, 7/24/91 Notes on Installation ===================== Dimensions and Mounting ----------------------- The GoDrive 80S differs only in terms of drive height @ 18.8mm 0.2mm, with the side mounting holes remaining 3.0mm 0.2mm from the drive bottom. The GoDrive 40/80S can be mounted in any orientation. Maximum screw penetration is 3 mm with three minimum penetration of three full threads, and with application of torque to these screws limited to 120 inch-ounces. If the bottom mounting holes are used, the surface to which the GoDrive is affixed must have a flatness of 0.127mm (0.005 inches) or better. Ventilation ----------- GoDrive 40/80 S hard disk drives operate without a cooling fan, provided the ambient air temperature does not exceed 55*C (131*F). Any user-designed cabinet must provide adequate air circulation to prevent the maximum temperature from being exceeded. Cable Connector --------------- The GoDrive 40/80S has a single 2 x 25 connector on 2mm centers for power, data and SCSI Address. The recommended mating connector on the system side is Dupont part number 69764-050 or equivalent. To prevent the possibility of in- correct installation, the hole of the mating connector that corres- ponds to Pin 17 of J1 should be plugged. The maximum cable length is 12 inches. Power Sequencing ---------------- The GoDrive 40/80S hard disk drive requires no power sequencing -- either OFF or ON. Applying or removing power during drive operation does not cause data to be lost or corrupted -- with the possible exception that data may be lost or corrupted in the sector being written at the time of a power loss. During power-on or power-off, the drive can sustain the shorting out or opening up of either voltage or return line. Although the GoDrive 40/80S hard disk drive requires no power sequencing, Quantum recommends that if a controlled power down is available from the system (e.g., in a system with an auto resume feature), a STOP command be issued to the drive prior to the removal power. ********************************************************************** F E A T U R E S ********************************************************************** QUANTUM GODRIVE 40/80S PRELIMINARY PRODUCT MANUAL REV. 0.5, 7/24/91 General Description ------------------- Quantum's GoDrive 40S and 80S hard disk drives are part of a family of high performance. 2.5 inch form factor hard disk drives manu- factured to meet the highest product-quality standards. GoDrive hard disk drives use non-removable, 2.5 inch rigid disks. Features -------- Key features of GoDrive 40/80 S hard disk drives include: - Embedded SCSI controller - Low-profile, optimized for number of disks - 112-bit Reed Solomon Error Correction Code (ECC), with 48-bit double burst correction - Proprietary 32K, look-ahead, programmable DisCache (8K on GoDrive 40S) with write Cache - Automatic retry on read errors - Transparent media-defect mapping - High performance, in-line defective sector skipping - Reassignment of defective sectors discovered in the field, without reformatting - Automatic actuator shipping lock and dedicated landing zone Seek Time --------- +-------------------------------+--------+ | | 40/80S | +-------------------------------+--------+ |Track-to-Track msec. typ. | 5 | +-------------------------------+--------+ |Average msec. typ. | 19 | +-------------------------------+--------+ |Full-Stroke msec. | 30 | +-------------------------------+--------+ |Latency msec. avg. | 8.3 | +-------------------------------+--------+ SCSIADR - SCSI Address (Byte 3, Bits 2-0): When SSID (bit 3 of byte 3) is set to one, SCSIADR determines the drive's SCSI ID. When chaning the SCSI ID with the MODE SELECT command, the SCSI ID will change immediately. If at initial power on, the SSID bit is set to one - that is, if this bit's previous setting was saved on the disk - the SCSIADR bit will determine the drive's SCSI ID. The default is zero. Defect Management ----------------- The format of the GoDrive 40/80S allocates one sector per cylinder as a spare. In the factory, the media is scanned for defects. If a sector on a cylinder is found to be defective, the sector's address is added to the drive's defect list. Sectors physically subsequent to the defective sectors are assigned logical block addresses such that a sequential ordering of logical blocks results. This inline sparing technique is employed in an attempt to eliminate throughput reduction resulting from a single defective sector on a cylinder. Should more than one sector be found to be defective on a cylinder, the in-line sparing approach is applied to the first sector only. The remaining defective sectors are replaced with the nearest available spare sectors on nearby cylinders. This assignment of additional replacement sectors from nearby cylinders rather than a central pool of spare sectors is an attempt to minimize the mechanical motion required to obtain the replacement sector. This results in the minimization of throughput reduction due to multiple defective sectors on a cylinder. Defects known as grown defects can occur in the field. If a defective sector is encountered, the sector is reallocated by the algorithm used in the factory to allocate the sectors found defective after the first defective sector on a cylinder. That is, in-line sparing to maintain the sequential nature of LBAs is not performed with grown defects. Sectors are considered to contain grown defects if the double burst ECC algorithm must be applied in an attempt to recover the desired data. If the double burst ECC algorithm was not successful, the erroneous data is stored in the newly allocated sector, and a flag is set in the data ID field; this causes the GoDrive to report an ECC error each time the sector is read until the sector is rewritten. Air Filtration -------------- The GoDrive Series hard disk drives are Winchster-type drives. The heads fly very close to the media surface, with a nominal flying height of 4.5 microinches. Therefore, it is essential that the air circulating within the drive be kept free of paticles. Quantum assembles the drive in a Class-100, purified air environment, then seals the drive with a metal cover. When the drive is in use, the rotation of the disks forces the air inside the drive through an internal filter. SCSI Electrical Characteristics ------------------------------- All signals are asserted, or true, at the low level, and use open- collector drivers terminated at each end of the cable with 1K ohm to +5 volts (nominal). On the drive, resistor networks terminate the lines. +-----------------------------------------------------------------+ |NOTE | |To connect multiple devices on a SCSI bus, remove the terminating| |resistors on all but the two devices at the cable ends. Because | |terminating resistors cannot be removed on the GoDrive, make sure| |that it is connected at one of the cable ends. | +-----------------------------------------------------------------+ Each signal driven by the GoDrive 40/80S hard disk drive has the following output characteristics: - True (signal assertion) = 0.0 to 0.5 volts DC at 48 milliamperes (maximum) - False (signal deassertion) = 2.5 to 5.25 volts DC Each signal from the host to the GoDrive 40/80S hard disk drive must have the following characteristics, as measured at the drive: - True (signal assertion) = 0.0 to 0.8 volts DC - False (signal deassertion) = 2.5 to 5.25 volts DC The drive uses a 40-pin SCSI-bus and DC power connector -- providing a single-ended, unshielded connection. All signals are asserted at the low level. Pin 17 is not connected and serves as a key to reduce the possibility of incorrect installation. Terminator Power ---------------- The GoDrive 40/80S hard disk drive supplies terminator power through a Schottky diode and a 1-amp fuse with the the following characteristics: VTERM = 4.25 volts DC to 5.25 volts DC 150 milliamperes minimum with 1K pullup resistors 800 milliamperes minimum source drive capability, if supplying external terminators 1.0 milliamperes maximum sink capability, except when providing power to an internal terminator 1.0 amp current limiting (fuse)

The form!

The state!

Question: what is the class of tvrdi disk

The form!

The state!

Question: what is the form of a tvrdi disk

The form!

The state!

class="wikitable" style="float: right; max-width: 50em; margin-left: 1.5em;" |+ Bivši i sadašnji obrasci za tvrde diskove |- ! Obrazac ! Stanje !

class="wikitable" style="float: right; max-width: 50em; margin-left: 1.5em;"♰+ Former and current formats for hard disks♰- ! The form! The state!

The form!
The state!
The length [mm] !

News Releases
Toshiba Introduces Industry's Largest-Capacity[1], 320GB 1.8-inch HDD16MB buffer memory and improved internal transfer rate support high-speed processing of large data volumes
TOKYO– Toshiba Corporation (TOKYO: 6502), the industry pioneer in small form factor hard disk drives (HDDs), today introduced a new line up of 1.8-inch HDDs with a maximum capacity of 320GB, the highest yet announced by the industry, targeted at thin and light mobile PCs and portable external hard disk drives. The new series delivers three models in 160GB, 250GB and 320GB capacities, and will start mass production from December.
Improvement of the MK3233GSG family's perpendicular magnetic recording head and the disk's magnetic layer secure an areal density of 801Mbit/mm2 (516Gbpsi), the industry's highest[2] for 1.8-inch HDDs. The new drives position Toshiba to provide manufacturers of PCs and peripheral equipment with thin and light solutions offering the industry's largest storage density in a 1.8-inch form factor. They also deliver highly efficient power consumption, high-level durability and quiet seek operation.
Equipped with a serial ATA interface, 5,400 RPM rotational speed and a large capacity 16MB buffer memory, Toshiba's MK3233GSG HDDs are ideal for notebook PC applications that require high storage capacity and high speed processing. The areal density improvement allows MK3233GSG to boost internal data transfer rates by 15% from the MK2529GSG, the company's earlier 250GB 1.8-inch HDD.
The new 250 and 320GB drives, the MK 2533GSG and MK3233GSG, cut acoustic noise during seek to 19dB, a 4dB decrease from the MK2529GSG, the top-end drive in Toshiba's previous generation of 5,400RPM 1.8-inch HDD.
Leveraging Toshiba's long history of expertise in miniaturization and the 1.8-inch HDD form factor, the MK3233GSG family delivers significant environmentally friendly performance improvements from the MK2529GSG generation of 1.8-inch drives, including a 19% improvement in energy consumption efficiency[3]. The MK3233GSG family is also compliant with the European Union's RoHS directive[4], halogen-free[5] and antimony free[6].
- [1]
- As of Nov. 5, 2009, for 1.8-inch HDD, source by Toshiba
- [2]
- As of Nov. 5, 2009, for 1.8-inch HDD, source by Toshiba
- [3]
- Energy consumption efficiency is calculated based on power consumption divided by formatted capacity, as defined by Japanese law.
- [4]
- The RoHS (Restriction of Hazardous Substances) directive, which came into effect on July 1, 2006 in the European Union, limits the use of various materials including lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls (PBB) and ploybrominated diphenyl ether (PBDE) in electronic and electronic equipment.
- [5]
- The new drives achieve chlorine and bromine concentrations below 900ppm, and a combined overall total below 1,500ppm, achieving the standard required for recognition as Toshiba environmentally conscious products (ECP).
- [6]
- The new drives have an antimony content below 1,000ppm, achieving the standard required at Toshiba.
Key Features
1.Areal density of 801 Mbit/mm2 (516Gbpsi) realizes the industry's largest[1] capacity 1.8-inch HDD (MK3233GSG)
MK3233GSG uses Toshiba technology to improve the perpendicular magnetic recording technology head and disk and realize the industry's highest areal density of 801 Mbit/mm2 (516 Gbpsi) and a capacity of 320GB, the industry's largest for a 1.8-inch HDD.
2.Improved high speed processing (all models)
MK3233GSG applies serial ATA interface which supports a 3.0Gbps data transfer rate, large capacity 16MB buffer memory and realize improved data processing compared to the 250GB MK2529GSG, the highest capacity model in Toshiba's previous series of 1.8-inch HDD. By improved linear recording density, internal data transfer rate is improved by 15%.
3.Improved seek noise (all models)
Toshiba's original advanced acoustic management technology limits acoustic noise during seek to 19dB in the MK3233GSG and MK2533GSG, a 4dB decreased against the previous MK2529GSG model. The MK1633GSG realizes 17dB, a 5dB decrease from the MK1229GSG.
4.Higher durability compared to 2.5-inch HDD
1.8-inch HDD are smaller, lighter, shock and vibration resistant than current 2.5-inch HDD mainly used in notebook PCs. 1.8-inch HDD will meet demand for thin and light mobile PCs and portable HDDs.
5.Environmentally Conscious products
(1) Halogen-Free Product, Antimony controlled
The new drives achieve chlorine and bromine concentrations below 900ppm, and a combined overall total below 1,500ppm. Antimony is also controlled at under 1,000ppm.
(2) Improved energy consumption efficiency (MK3233GSG)
Compared to the 250GB (MK2529GSG), the new 320GB HDD model (MK3233GSG) improves energy consumption efficiency, as defined under the Japanese legal standard; a full 19% improvement.
(3) Decreased CO2 amount during lifecycle[7] (MK3233GSG)
MK3233GSG decreases CO2 emissions across the product lifecycle by 36g per year, by decreasing product power consumption and environmental burdens from the raw materials stage.
(4) RoHS compliant
The new drives comply with the European Union's RoHS directive on the elimination of six hazardous substances in electrical and electronic equipment.
(5) Meets standards for certification as Toshiba ECP
Toshiba promotes an "Excellent ECP" program to stimulate creation of high value products offering exceptional environmental friendliness. For more information, visit
http://www.toshiba.co.jp/env/en/products/index.htm
Toshiba Group, a corporate citizen of planet Earth, is committed to realizing a better environment. Guided by "Toshiba Group Environmental Vision 2050" the Group is implementing measures to boost environmental efficiency by 10 times in FY2050, against the benchmark of FY2000. The core target is to reduce projected CO2 emissions by a total equivalent to 117.7 million tons a year by FY2025, through the development and sales of highly efficient power supply equipment and systems, and the manufacture of environmentally conscious home appliances and office equipment. By working to mitigate global warming, make efficient use of resources and control management of chemicals, Toshiba Group creates value for people and promotes lifestyles in harmony with the Earth.
Product Specifications
|Model Number||MK3233GSG||MK2533GSG||MK1633GSG|
|Capacity||320GB||250GB||160GB|
|Number of disks||2||1|
|Number of heads||4||2|
|Average seek time||15 ms|
|Interface||SATA|
|Interface speed||3.0Gbps|
|Rotational speed||5,400 rpm|
|Buffer memory||16MB|
|External dimensions||(W)54.0 mm × (D)78.5 mm × (H)8.0 mm|
|Weight||62g (max)||60g (max)|
|Power consumption||Seek||1.3W|
|Read/Write||1.3W|
|Energy consumption efficiency||0.0013||0.0016||0.0025|
|Category name[8]||h||h||g|
|Acoustics||Idle||18dB||16dB|
|Seek||19dB||17dB|
|Vibration resistance||Operating||19.6 m/s2 , 2.0G (15-500Hz)|
|Non-operating||49 m/s2 , 5.0G (15-500Hz)|
|Shock resistance||Operating||4,900 m/s2 (500G , 2ms)|
|Non-operating||14,700 m/s2 (1,500G , 1ms)|
One Gigabyte (1 GB) means 109 =1,000,000,000 bytes using powers of 10. A computer operating system, however, reports storage capacity using powers of 2 for the definition of 1 GB = 230= 1,073,741,824 bytes, and therefore shows less storage capacity. Available storage capacity (including examples of various media files) will vary based on file size, formatting, settings, software and operating system. Examples of the number of photos, songs, movies, and any other files that can be stored on a hard drive are provided for illustrative purposes only. Your results will vary based on file size and format, settings, features, operating system, software and other factors.
- [7]
- Comparison based on MK6008GAH (Year 2005 model). Based on Toshiba's evaluation method of LCA (Life Cycle Assesment).
- [8]
- Category names defined by Japan's Ministry of Economy, Trade and Industry are applied in the Japanese market.

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The SDK Starts Shipments of 1.3-Inch PMR-Technology-Based HD Media (2007)

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The 1 GB, 0.85 inch hard disk drive exists Toshiba Enters Guinness World Records Book with the World's Smallest Hard Disk Drive (2004.)

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| Toshiba Enters Guinness World Records Book with the World's Smallest Hard Disk Drive
|
16 March, 2004
TOKYO -- Toshiba Corporation today announced that Guinness World Records has certified Toshiba's 0.85-inch hard disk drive (HDD) as the smallest HDD in the world and will feature it in the 2005 edition, scheduled to be on sale in September 2004. The Guinness World Records Book is one of the world's most popular publications, the book most people reach for when they want to confirm outstanding achievements in all walks of life.
Toshiba's 0.85-inch HDD, announced in January 2004, is the first hard disk drive to deliver multi-gigabyte data storage in a sub-one-inch form factor. The 0.85-inch measurement refers to the diameter of the magnetic disk to which data is recorded. With initial capacities of 2 to 4 gigabytes (GB) the drive delivers enhanced storage to smaller, lighter, more efficient products, such as mobile phones, digital camcorders and portable storage devices. Toshiba expects to start sampling the drive in summer 2004 and to start mass production in autumn 2004.
For more details of Toshiba's 0.85-inch HDD, please see:
"We are very proud that Guinness World Records, one of the world's most famous organisations, has recognised our 0.85-inch HDD as the world's smallest," said Kazuyoshi Yamamori, Vice President of Storage Device Division at Toshiba Corporation's Digital Media Network Company. "Toshiba is the global leader in small form factor hard disk drives. Our 1.8-inch HDD opened up exciting new applications and markets, including powerful digital audio players, and we expect the 0.85-inch disk to contribute even more. I look forward to seeing the 0.85-inch drive alongside all the other record breakers and winners in the book."
David Hawksett, Science & Technology editor at Guinness World Records said: "Hard drive technology has come a long way since the introduction of the very first model in the U.S. in 1956. That model needed 50 two-foot disks to store just 4.4 MB and the cost was astronomical. Data storage is rarely a topic that excites the public. However, Toshiba's innovation means that I could soon hold more information in my watch than I could on my desktop computer, just a few years ago."
Selection for the best-selling book is the latest recognition of Toshiba's achievements as a global leader in small form factor HDDs. Toshiba has consistently led innovation of the 1.8-inch HDD market, including being the first to commercialise a 40GB version, and recording a cumulative production of 3-million units in October 2003. In the 2.5-inch HDD segment, the company's cumulative production now surpasses 60 million units. Toshiba expects its development of the 0.85-inch HDD to expand the market for miniature drives and will continue to promote innovations that assure its continued leadership in that market.
Toshiba will feature the 0.85-inch drive at CeBIT in Hannover, Germany, from March 18 to 24.
Note: Currently the 1.0-inch HDD is the smallest device commercially available.
About Guinness World Records:
First published in 1955, Guinness World RecordsTM has developed its annual book into an international phenomenon published in more than 100 countries and 23 languages. Guinness World Records has become a household name and the global leader in world records. No other enterprise collects, confirms, accredits and presents world record data with the same investment in comprehensiveness and authenticity. Guinness World Records is the universally recognised authority on record-breaking achievement.
About Toshiba Corporation:
Toshiba Corporation is a leader in information and communications systems, electronic components, consumer products and power systems. The company's integration of these wide-ranging capabilities assures its position as an innovator in advanced components, products and systems. Toshiba has more than 166,000 employees worldwide and annual sales of over US$47 billion in fiscal year 2002.
|Information in the press releases, including product prices and specifications, content of services and contact information, is current on the date of the press announcement,but is subject to change without prior notice.|

|- | 8-cola | | 362 | 241,3 | 117,5 | | | |- | 5,25-cola FH | | 203 | 146 | 82,6 | 47 GBSeagate Elite 47, shipped 12/97 per 1998 Disk/Trend Report – Rigid Disk Drives (1998.) | 14 | 3,36 |- | 5,25-cola HH | | 203 | 146 | 41,4 | 19,3 GBQuantum Bigfoot TS, shipped 10/98 per 1999 Disk/Trend Report – Rigid Disk Drives (1998.) | 4 | 4,83 |- | 1,3-cola | | | 43 | | 40 GB , SDK Starts Shipments of 1.3-Inch PMR-Technology-Based HD Media (2007.) | 1 | 40 |- | 1-cola (CFII/ZIF/IDE-Flex) | | | 42 | | 20 GB (2006.) | 1 | 20 |- | 0,85-cola | | 32 | 24 | 5 | 8 GB Proving that 8 GB, 0.85 inch hard disk drive exists Toshiba Enters Guinness World Records Book with the World's Smallest Hard Disk Drive (2004.) | 1 | 8 |}

| 4 | 4,83 |- | 1,3-cola | | | 43 | | 40 GB , SDK Starts Shipments of 1.3-Inch PMR-Technology-Based HD Media (2007.)

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The SDK Starts Shipments of 1.3-Inch PMR-Technology-Based HD Media (2007)

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