text: Google Spans Entire Planet With Gps-Powered Database | News | Communications of the ACM
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  A new Google research paper details the workings of the Spanner data storage and compilation system, billed as the first database capable of quickly storing and retrieving information across a worldwide network of data centers while maintaining the information's consistency.
  Spanner interfaces with a network of servers outfitted with atomic clocks or global positioning system (GPS) antennas to facilitate accurate synchronization of data distribution. Spanner can store data across millions of servers and multiple data centers using the TrueTime applications programming interface (API), which employs the atomic clocks and GPS antennas to ensure that network operations run in tandem.
  Google spreads clocks across its network instead of attempting to enhance communication between servers. It outfits various master servers with GPS antennas or atomic clocks and, working in lockstep with the TrueTime APIs, these time keepers maintain synchronization across the entire network. TrueTime communicates to the servers the degree of uncertainty there is over the current time, and they can modify their reads and writes accordingly. Google researchers say Spanner helps the company replicate and route data across its network, and augments data center upgrades and repairs.