# lv with btrfs corrupt - some tips please

**URL:** <https://forums.suse.com/t/lv-with-btrfs-corrupt-some-tips-please/30454>\
**Category:** SLES Configure-Administer\
**Created:** [October 18, 2017, 7:10pm UTC](https://forums.suse.com/t/lv-with-btrfs-corrupt-some-tips-please/30454 "2017-10-18T19:10:21Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![berndgsflinux](https://avatars.discourse-cdn.com/v4/letter/b/6a8cbe/32.png) [@berndgsflinux](https://forums.suse.com/u/berndgsflinux)\
**Post date:** [October 18, 2017, 7:10pm UTC](https://forums.suse.com/t/lv-with-btrfs-corrupt-some-tips-please/30454/1 "2017-10-18T19:10:21Z")

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Hi,  
i have a corrupt btrfs in which my / resides. I can’t mount it anymore. System does not boot, it resides in a very limited shell. This is my first corrupt linux filesystem, i was lucky all the years doing system administration :-)) So i’m a bit nervous and don’t know exactly what to do. Who has experience with corrupt btrfs ? Shall i try to repair with the SLES installation cd or prefer a knoppix ? Or from this limited shell ?

Thanks for any tip.

Bernd

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**Author:** ![malcolmlewis](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/malcolmlewis/32/11375_2.png) [@malcolmlewis](https://forums.suse.com/u/malcolmlewis)\
**Post date:** [October 19, 2017, 3:12am UTC](https://forums.suse.com/t/lv-with-btrfs-corrupt-some-tips-please/30454/2 "2017-10-19T03:12:59Z")

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Hi  
If you boot from the install medium in rescue mode and look at the following commands;

```auto
btrfs rescue --help

usage: btrfs rescue <command> [options] <path>

    btrfs rescue chunk-recover [options] <device>
        Recover the chunk tree by scanning the devices one by one.
    btrfs rescue super-recover [options] <device>
        Recover bad superblocks from good copies
    btrfs rescue zero-log <device>
        Clear the tree log. Usable if it's corrupted and prevents mount.

toolbox for specific rescue operations

btrfs check --help

usage: btrfs check [options] <device>

    Check structural inegrity of a filesystem (unmounted).

    Check structural inegrity of an unmounted filesystem. Verify internal
    trees' consistency and item connectivity. In the repair mode try to
    fix the problems found.
    WARNING: the repair mode is considered dangerous

    -s|--super <superblock> use this superblock copy
    -b|--backup use the first valid backup root copy
    --repair try to repair the filesystem
    --readonly run in read-only mode (default)
    --init-csum-tree create a new CRC tree
    --init-extent-tree create a new extent tree
    --check-data-csum verify checkums of data blocks
    -Q|--qgroup-report print a report on qgroup consistency
    -E|--subvol-extents <subvolid>
                                print subvolume extents and sharing state
    -r|--tree-root <bytenr> use the given bytenr for the tree root
    --chunk-root <bytenr> use the given bytenr for the chunk tree root
    -p|--progress indicate progress
```

I would guess it’s either supper-recover or zero-log (since you can’t mount) that may help.

So you can’t even boot from a previous snapshot?

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<div class="post-metadata">

**Author:** ![berndgsflinux](https://avatars.discourse-cdn.com/v4/letter/b/6a8cbe/32.png) [@berndgsflinux](https://forums.suse.com/u/berndgsflinux)\
**Post date:** [October 19, 2017, 8:55pm UTC](https://forums.suse.com/t/lv-with-btrfs-corrupt-some-tips-please/30454/3 "2017-10-19T20:55:51Z")

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Hi Malcom,

thanks for your help. But i asked now on the btrfs ML, which i think is a more appropriate place ([https://btrfs.wiki.kernel.org/index.php/Btrfs\_mailing\_list](https://btrfs.wiki.kernel.org/index.php/Btrfs_mailing_list)). Discussing the same topic on two places is a waste of resources, so i propose not to continue here.  
Nevertheless thanks for your help.

Bernd