On 19/02/2019 12:34, Qu Wenruo wrote:
On 2019/2/19 下午6:24, Roderick Johnstone wrote:
Hi
This is on Fedora 28:
# uname -a
Linux mysystem.mydomain 4.20.7-100.fc28.x86_64 #1 SMP Wed Feb 6 19:17:09
UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
# btrfs --version
btrfs-progs v4.17.1
# btrfs fi show
Label: none uuid: 56d0171a-440d-47ff-ad0f-f7f97df31f7b
Total devices 1 FS bytes used 7.39TiB
devid 1 size 9.10TiB used 7.50TiB path /dev/md2
My btrfs filesystem is in a bad state after a partial disk failure on
the md device (raid 6 array) the file system was on.
One of the disks had bad blocks, but instead of being ejected from the
array, the array hung up.
I'm a little interested why RAID6 hung up.
I'm not sure but I think it was due to the failure more of the hardware.
After rebooting to regain access and remove
the bad disk I am in the following situation:
# mount -t btrfs -o compress-force=zlib,noatime /dev/md2 /mnt/rmj
mount: /mnt/rmj: wrong fs type, bad option, bad superblock on /dev/md2,
missing codepage or helper program, or other error.
# dmesg
...
264.527647] BTRFS info (device md2): force zlib compression, level 3
[ 264.955360] BTRFS error (device md2): parent transid verify failed on
5568287064064 wanted 254988 found 94122
It's 99% some extent tree blocks get corrupted.
[ 264.964273] BTRFS error (device md2): open_ctree failed
I can mount and access the filesystem with the usebackuproot option:
# mount -t btrfs -o usebackuproot,compress-force=zlib,noatime /dev/md2
/mnt/rmj
[ 307.542761] BTRFS info (device md2): trying to use backup root at
mount time
[ 307.542768] BTRFS info (device md2): force zlib compression, level 3
[ 307.570897] BTRFS error (device md2): parent transid verify failed on
5568287064064 wanted 254988 found 94122
[ 307.570979] BTRFS error (device md2): parent transid verify failed on
5568287064064 wanted 254988 found 94122
[ 431.167149] BTRFS info (device md2): checking UUID tree
But later after a umount there are these messages.
# umount /mnt/rmj
2205.778998] BTRFS error (device md2): parent transid verify failed on
5568276393984 wanted 254986 found 94117
[ 2205.779008] BTRFS: error (device md2) in __btrfs_free_extent:6831:
errno=-5 IO failure
[ 2205.779082] BTRFS info (device md2): forced readonly
[ 2205.779087] BTRFS: error (device md2) in btrfs_run_delayed_refs:2978:
errno=-5 IO failure
[ 2205.779192] BTRFS warning (device md2): btrfs_uuid_scan_kthread
failed -30
Of course it's extent tree corrupted.
and a subsequent mount without the userbackuproot fails in the same way
as before.
I have a copy of the important directories, but would like to be able to
repair the filesystem if possible,
You could mostly salvage the data, either use 'usebackuproot' mount
option + RO mount or btrfs-restore.
For full rw recovery, I don't think there is a good tool right now.
Extent tree repair is pretty trikcy, under most case, the only method is
--init-extent-tree, but that functionality isn't tried by many users.
And it only makes sense if all other trees are OK.
So in short, RW recovery is near impossible.
Any advise around repairing the filesystem would be appreciated.
It's better to salvage your data first and if you like adventure, try
--init-extent-tree.
If not, just rebuild the array.
ok, thanks.
Roderick
Thanks,
Qu
Thanks.
Roderick Johnstone
