Q:

repartitioning a qcow2 image without data loss

I'm experimenting with repartitioning in a KVM virtual. I have created a new qcow2 disk and mounted in a virtual. I'm experimenting with resizing the filesystem and repartitioning. I had previously unmounted and shrunk the filesystem using e2fsk -f and then resize2fs -M down to around 30k blocks. From what I've read online, to shrink the partition I now need to delete it, and then recreate it with a smaller block count (no less than the size of my file system) at the same starting sector. When I use fdisk to delete partition 1, and then recreate it, my lowest starting sector is 2048. As you can see in the output below, partition 1 originally starts at sector 8. What am I doing incorrectly?
pphan@www-dev1:~$ mount -l -t ext3
/dev/vdb1 on /wsrv type ext3 (rw)
pphan@www-dev1:~$ sudo umount /wsrv
pphan@www-dev1:~$ sudo fdisk -u -c -l /dev/vdb

Disk /dev/vdb: 1073 MB, 1073741824 bytes
9 heads, 8 sectors/track, 29127 cylinders, total 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xad16440c

   Device Boot      Start         End      Blocks   Id  System
/dev/vdb1               8     2097143     1048568   83  Linux

Ubuntu 10.04.2 host and guest. I have tagged libvirt-KVM because I am not sure if this problem is specific to disk images.
TIA

A:

This happens with physical disks as well. To be able to specify a lower initial sector, launch fdisk with the -cu options. You can also go to expert menu ('x') and use "move beginning of data in a partition" ('b') command.

