FWIW, I figured out the ceph "out of memory" error that was keeping me from
recovering one FS:

# ls -l /mnt
ls: cannot access /mnt/snap_3415219: Cannot allocate memory
total 5242920
-rw-r--r-- 1 root root        472 May 23 19:16 activate.monmap
-rw-r--r-- 1 root root          3 May 23 19:16 active
-rw-r--r-- 1 root root         37 May 23 19:14 ceph_fsid
drwxr-xr-x 1 root root      11688 May 31 15:10 current
-rw-r--r-- 1 root root         37 May 23 19:14 fsid
-rw-r--r-- 1 root root 5368709120 Jun  2 08:11 journal
-rw------- 1 root root         56 May 23 19:16 keyring
-rw-r--r-- 1 root root         21 May 23 19:14 magic
-rw-r--r-- 1 root root          6 May 23 19:16 ready
d????????? ? ?    ?             ?            ? snap_3415219
drwxr-xr-x 1 root root      11688 May 31 15:10 snap_3415260
drwxr-xr-x 1 root root      11688 May 31 15:10 snap_3415296
-rw-r--r-- 1 root root          4 May 23 19:16 store_version
-rw-r--r-- 1 root root         69 May 29 22:34 superblock
-rw-r--r-- 1 root root          0 May 23 19:16 upstart
-rw-r--r-- 1 root root          2 May 23 19:16 whoami

snap_3415219 is clearly corrupt.  I'm going to duplicate the filesystem
(it's only 50G, doesn't take long) without the file and see if that'll work.


On Mon, Jun 2, 2014 at 9:51 AM, Dmitry Smirnov <[email protected]>
wrote:

> On Mon, 2 Jun 2014 17:47:57 Thorwald Lundqvist wrote:
> > I'd say don't use btrfs at all, it has proven unstable for us in
> production
> > even without cache. It's just not ready for production use.
>
> Perception of stability depends on experience. For instance some consider
> XFS
> to be ready for production but it does not tolerate power loss which lead
> to
> loss of data. Also fixing corrupted XFS may not be possible due to
> xfs_repair
> memory requirements.
>
> Ready for production or not depends on testing (building confidence) and
> understanding limitations. As a matter of fact Btrfs is very stable and
> reliable on recent kernels (3.11+) if used pretty much as ext4 i.e. without
> advanced features (e.g. snapshots, subvolumes etc.).
>
> Linux 3.14.1 is affected by serious Btrfs regression(s) that were fixed in
> later releases.
>
> Unfortunately even latest Linux can crash and corrupt Btrfs file system if
> OSDs are using snapshots (which is the default). Due to kernel bugs
> related to
> Btrfs snapshots I also lost some OSDs until I found that snapshotting can
> be
> disabled with "filestore btrfs snap = false".
>
> So far I'm very happy with Btrfs stability on OSDs when snapshots are
> disabled.
>
> --
> Cheers,
>  Dmitry Smirnov
>  GPG key : 4096R/53968D1B
>
> ---
>
> Every decent man is ashamed of the government he lives under.
>         -- H. L. Mencken
>
> _______________________________________________
> ceph-users mailing list
> [email protected]
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>
>
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