Re: Broken Filesystem

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2020/1/25 下午7:34, Hendrik Friedel wrote:
> Hello,
> 
> I am helping someone here
> https://forum.openmediavault.org/index.php/Thread/29290-Harddrive-Failure-and-Data-Recovery/?postID=226502#post226502
>  to recover his data.
> He is new to linux.
> 
> Two of his drives have a hardware problem.
> btrfs filesystem show /dev/sda
> Label: 'sdadisk1' uuid: fdce5ae5-fd6d-46b9-8056-3ff15ce9fa16
> Total devices 1 FS bytes used 128.00KiB
> devid 1 size 931.51GiB used 4.10GiB path /dev/sda
> 
> The 4.1GiB are way less than what was used.
> 
> 
> We tried to mount with mount -t btrfs -o recovery,nospace_cache,clear_cache
> 
> [Sat Jan 18 11:40:29 2020] BTRFS warning (device sda): 'recovery' is
> deprecated, use 'usebackuproot' instead
> [Sat Jan 18 11:40:29 2020] BTRFS info (device sda): trying to use backup
> root at mount time
> [Sat Jan 18 11:40:29 2020] BTRFS info (device sda): disabling disk space
> caching
> [Sat Jan 18 11:40:29 2020] BTRFS info (device sda): force clearing of
> disk cache
> [Sun Jan 19 11:58:24 2020] BTRFS warning (device sda): 'recovery' is
> deprecated, use 'usebackuproot' instead
> [Sun Jan 19 11:58:24 2020] BTRFS info (device sda): trying to use backup
> root at mount time
> [Sun Jan 19 11:58:24 2020] BTRFS info (device sda): disabling disk space
> caching
> [Sun Jan 19 11:58:24 2020] BTRFS info (device sda): force clearing of
> disk cache
> 
> 
> The mountpoint does not show any data when mounted
> 
> Scrub did not help:
> btrfs scrub start /dev/sda
> scrub started on /dev/sda, fsid fdce5ae5-fd6d-46b9-8056-3ff15ce9fa16
> (pid=19881)
> 
> btrfs scrub status /dev/sda
> scrub status for fdce5ae5-fd6d-46b9-8056-3ff15ce9fa16
> scrub started at Sun Jan 19 12:03:35 2020 and finished after 00:00:00
> total bytes scrubbed: 256.00KiB with 0 errors
> 
> 
> btrfs check /dev/sda
> Checking filesystem on /dev/sda
> UUID: fdce5ae5-fd6d-46b9-8056-3ff15ce9fa16
> checking extents
> checking free space cache
> cache and super generation don't match, space cache will be invalidated
> checking fs roots
> checking csums
> checking root refs
> found 131072 bytes used err is 0
> total csum bytes: 0
> total tree bytes: 131072
> total fs tree bytes: 32768
> total extent tree bytes: 16384
> btree space waste bytes: 123986
> file data blocks allocated: 0
> referenced 0

Your fs is completely fine. I didn't see anything wrong from your `btrfs
check` result nor your kernel messages.

> 
> 
> Also btrfs restore -i -v /dev/sda /srv/dev-disk-by-label-NewDrive2 | tee
> /restorelog.txt did not help:
> It came immediately back with 'Reached the end of the tree searching the
> directory'
> 
> 
> btrfs-find-root /dev/sda
> Superblock thinks the generation is 8
> Superblock thinks the level is 0
> It did not finish even in 54 hours
> 
> I am out of ideas. Can you give further advice?

Since your fs is OK, what's wrong?

Maybe just mounted wrong subvolume?

Thanks,
Qu

> 
> Regards,
> Hendrik
> 


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