Re: Filesystem corrupted, is there any hope?

["Fajar A. Nugraha" <list@fajar.net>]

On Fri, Jun 24, 2011 at 5:16 PM, Michael Stephenson
<mickstephenson@googlemail.com> wrote:
> Hello,
> I formatted my home partition with btrfs, not realising that the fsck
> tool can't actually fix errors, as I have just discovered on your
> wiki.
> Had I knew this I would have not used it so early, this detail you
> would think would make distributions wary to make it an option on the
> livecd with no warning that if you ever have a power cut you are most
> certainly going to lose your data even if your hardware is fine.
> Anyway is their any hope? Is there beta code for an fsck that can do
> repairs? How long do I have to wait before there is? I can always just
> wait for a few months to get the data back.

That depends on what kind of corruption you have (dmesg / syslog
output would be nice)

For some cases, you can try:
- "btrfsck -s1", and if can finish without errors, try  btrfs-select-super
- if it complains about some transid not available, try btrfs-zero-log

both btrfs-select-super and btrfs-zero-log need to be compiled
manually from source (i.e. "make btrfs-select-super" and "make
btrfs-zero-log"). if you use lzo, you might need the tmp branch
(http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-progs-unstable.git;a=shortlog;h=refs/heads/tmp)

Some more suggestions:
- when possible, create a copy first of the device (e.g. with
dd_rescue) and work on the copy
- use "mount -o ro", and if readonly mount is successful, copy the
files somewhere safe and recreate your fs.

-- 
Fajar