Bug#637234: linux-image-3.0.0-1-686-pae: I/O errors using ext4 under xen

[Gedalya <gedalya@gedalya.net>]

This has already been reported here:
http://www.mail-archive.com/ubuntu-server@lists.ubuntu.com/msg05621.html

Generally I use lvm2 as storage backend, but I've just reproduced the 
exact same behavior using raw image files.

I get the following exactly every other time the VM boots:

[    6.837760] end_request: I/O error, dev xvda, sector 4456680
[    6.837783] end_request: I/O error, dev xvda, sector 4456680
[    6.837824] Aborting journal on device xvda-8.
[    6.845859] EXT4-fs error (device xvda): ext4_journal_start_sb:296: 
Detected aborted journal
[    6.845945] EXT4-fs (xvda): Remounting filesystem read-only


The following time it runs fsck:

Checking root file system...fsck from util-linux 2.19.1
/dev/xvda contains a file system with errors, check forced.
/dev/xvda: 26427/327680 files (0.2% non-contiguous), 196522/1310720 blocks
done.

and then seems to work fine, until the next reboot.