[Qemu-discuss] Fwd: Re: qemu-img resize corrupted image?

[Tony Su]

---------- Forwarded message ----------
From: "Tony Su" <address@hidden>
Date: Oct 21, 2013 8:27 AM
Subject: Re: [Qemu-discuss] qemu-img resize corrupted image?
To: "Ray Morris" <address@hidden>
Cc:

Although I haven't tried to repair a qcow image specifically,
In general the first step in any recovery is to mount the disk.

A quick Google returns a number of solutions, all the ones I've read suggest that the nbd utility (network block device) should be able to mount qcow images. After that, if you can read your disk you should be able to perform repairs.

Needless to say,
- Backups should always be made before performing any risky disk alterations
- Backups should be made before new alterations, so regardless whether you copied the disk file before re-sizing, you should make new copies before attempting to mount and repair.
- With 20/20 hindsight, I guess the question has to be asked how you could consider re-sizing a disk which was already known to be faulty. Prerequisites to resizing should have been to ensure disk file integrity (fschk) and zero the empty space.

Some Google links which look promising
http://www.randomhacks.co.uk/ho-to-recover-fsck-a--file/
http://mail-archive.com/address@hidden/msg30815.html

And, of course the cautious would always re-size a <copy> of the disk file, not the production disk file itself.

Good Luck,
Tony