Shrinking EBS Volume

Posted bylantean

It took me a while to shrink my EBS volume, but this post helped quite a lot.
For further reference, this are the exact steps i’ve performed:

  1. Created a snapshot of the EBS volume, for backup reasons.
  2. Added a new volume, based on the snapshot.
  3. Added another volume with the desired size.
  4. Attached both, the Normal and Shrunken volumes.
  5. Check the big volume, and resize it:

    [cc]
    e2fsck -f /dev/bigvolume
    resize2fs -M -p /dev/bigvolume
    [/cc]

  6. Note that ‘resize2fs’ will say something like:
    [cc]Resizing the filesystem on /dev/xvdg to 1035624 (4k) blocks.[/cc]
  7. Let’s calculate how many 16MB blocks we’ll need:
    [cc]x = 1035624 * 4 / 1024 / 16 = 253[/cc]
  8. Proceed copy’ing blocks to the small volume:
    [cc]dd bs=16M if=/dev/bigvolume of=/dev/smallvolume count=253[/cc]
  9. Resize + Check the small volume:
    [cc]
    resize2fs -p /dev/smallvolume
    e2fsck -f /dev/smallvolume
    [/cc]
  10. Stop the instance.
  11. Detach the 3 volumes: Root, Big and Small.
  12. Attach the Small volume at the same location as the previous root volume was. In my case, /dev/sda1.
  13. Ready!
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