On Thu, Dec 6, 2018 at 10:24 PM Doni Crosby <doni.crosby1995@xxxxxxxxx> wrote:
>
> All,
>
> I'm coming to you to see if there is a way to fix or at least recover
> most of the data I have from a btrfs filesystem. The system went down
> after both a breaker and the battery backup failed. I cannot currently
> mount the system, with the following error from dmesg:
>
> Note: The vda1 is just the entire disk being passed from the VM host
> to the VM it's not an actual true virtual block device
This is qemu-kvm? What's the cache mode being used? It's possible the
usual write guarantees are thwarted by VM caching.
> btrfs check --recover also ends in a segmentation fault
I'm not familiar with --recover option, the --repair option is flagged
with a warning in the man page.
Warning
Do not use --repair unless you are advised to do so by a
developer or an experienced user,
> btrfs --version:
> btrfs-progs v4.7.3
Old version of progs, I suggest upgrading to 4.17.1 and run
btrfs insp dump-s -f /device/
btrfs insp rescue super -v /device/
btrfs check --mode=lowmem /device/
These are all read only commands. Please post output to the list,
hopefully a developer will get around to looking at it.
It is safe to try:
mount -o ro,norecovery,usebackuproot /device/ /mnt/
If that works, I suggest updating your backup while it's still
possible in the meantime.
--
Chris Murphy
