[Bug 1310652] [NEW] btrfs filesystem contents disappeared after reboot

Márcio Santos 1310652 at bugs.launchpad.net
Mon Apr 21 14:44:01 UTC 2014


Public bug reported:

Running a multi disk RAID 1 with btrfs for a while now on a Virtual Lab Server with Ubuntu 14.04 amd64.
Today, after a clean reboot due to power failure initiated by the NUTS Daemon, when the system came back online, the filesystem of this specific RAID 1 disappeared.

df -h shows very little disk space used in the RAID 1:
    /dev/sdb        597G   80M  595G   1% /kvm

ls -las /kvm shows no files:
    total 4
    4 drwxr-xr-x 1 root root   0 Apr 21 11:26 .
    0 drwxr-xr-x 1 root root 186 Apr 14 00:35 ..

btrfs filesystem show /kvm shows that apparently the previous information is still in the hard drives:
    Label: none  uuid: 45075b5b-a389-445a-b70e-00a1bfcd313a
            Total devices 2 FS bytes used 39.68MiB
            devid    1 size 298.09GiB used 158.03GiB path /dev/sda
            devid    2 size 298.09GiB used 158.03GiB path /dev/sdb
Btrfs v3.12

No subvolumes or snapshots exist, since no output is given from btrfs
subvolume list /kvm

Running a scrub on the RAID 1 completes successfully, with no errors found, but only processes approximatle 80Mb of files:
    scrub status for 45075b5b-a389-445a-b70e-00a1bfcd313a
            scrub started at Mon Apr 21 15:37:55 2014 and finished after 1 seconds
            total bytes scrubbed: 79.36MiB with 0 errors

Running a FS Check on both hard drives reveals no errors:
    Checking filesystem on /dev/sda
    UUID: 45075b5b-a389-445a-b70e-00a1bfcd313a
    checking extents
    checking free space cache
    checking fs roots
    checking csums
    checking root refs
    found 4382862 bytes used err is 0
    total csum bytes: 0
    total tree bytes: 188416
    total fs tree bytes: 8192
    total extent tree bytes: 36864
    btree space waste bytes: 57988
    file data blocks allocated: 41418752
     referenced 41418752
    Btrfs v3.12

    Checking filesystem on /dev/sdb
    UUID: 45075b5b-a389-445a-b70e-00a1bfcd313a
    checking extents
    checking free space cache
    checking fs roots
    checking csums
    checking root refs
    found 4382862 bytes used err is 0
    total csum bytes: 0
    total tree bytes: 188416
    total fs tree bytes: 8192
    total extent tree bytes: 36864
    btree space waste bytes: 57988
    file data blocks allocated: 41418752
     referenced 41418752
    Btrfs v3.12

Tried to perform a restore on one of the hard drives, but no information
was recovered.

Would really appreciate some feedback on this one, could be a really
serious btrfs bug.

Kind regards,

Márcio Santos

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: btrfs-tools 3.12-1
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
Date: Mon Apr 21 15:29:28 2014
SourcePackage: btrfs-tools
UpgradeStatus: Upgraded to trusty on 2014-03-21 (30 days ago)

** Affects: btrfs-tools (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug trusty

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https://bugs.launchpad.net/bugs/1310652

Title:
  btrfs filesystem contents disappeared after reboot

Status in “btrfs-tools” package in Ubuntu:
  New

Bug description:
  Running a multi disk RAID 1 with btrfs for a while now on a Virtual Lab Server with Ubuntu 14.04 amd64.
  Today, after a clean reboot due to power failure initiated by the NUTS Daemon, when the system came back online, the filesystem of this specific RAID 1 disappeared.

  df -h shows very little disk space used in the RAID 1:
      /dev/sdb        597G   80M  595G   1% /kvm

  ls -las /kvm shows no files:
      total 4
      4 drwxr-xr-x 1 root root   0 Apr 21 11:26 .
      0 drwxr-xr-x 1 root root 186 Apr 14 00:35 ..

  btrfs filesystem show /kvm shows that apparently the previous information is still in the hard drives:
      Label: none  uuid: 45075b5b-a389-445a-b70e-00a1bfcd313a
              Total devices 2 FS bytes used 39.68MiB
              devid    1 size 298.09GiB used 158.03GiB path /dev/sda
              devid    2 size 298.09GiB used 158.03GiB path /dev/sdb
  Btrfs v3.12

  No subvolumes or snapshots exist, since no output is given from btrfs
  subvolume list /kvm

  Running a scrub on the RAID 1 completes successfully, with no errors found, but only processes approximatle 80Mb of files:
      scrub status for 45075b5b-a389-445a-b70e-00a1bfcd313a
              scrub started at Mon Apr 21 15:37:55 2014 and finished after 1 seconds
              total bytes scrubbed: 79.36MiB with 0 errors

  Running a FS Check on both hard drives reveals no errors:
      Checking filesystem on /dev/sda
      UUID: 45075b5b-a389-445a-b70e-00a1bfcd313a
      checking extents
      checking free space cache
      checking fs roots
      checking csums
      checking root refs
      found 4382862 bytes used err is 0
      total csum bytes: 0
      total tree bytes: 188416
      total fs tree bytes: 8192
      total extent tree bytes: 36864
      btree space waste bytes: 57988
      file data blocks allocated: 41418752
       referenced 41418752
      Btrfs v3.12

      Checking filesystem on /dev/sdb
      UUID: 45075b5b-a389-445a-b70e-00a1bfcd313a
      checking extents
      checking free space cache
      checking fs roots
      checking csums
      checking root refs
      found 4382862 bytes used err is 0
      total csum bytes: 0
      total tree bytes: 188416
      total fs tree bytes: 8192
      total extent tree bytes: 36864
      btree space waste bytes: 57988
      file data blocks allocated: 41418752
       referenced 41418752
      Btrfs v3.12

  Tried to perform a restore on one of the hard drives, but no
  information was recovered.

  Would really appreciate some feedback on this one, could be a really
  serious btrfs bug.

  Kind regards,

  Márcio Santos

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: btrfs-tools 3.12-1
  ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
  Uname: Linux 3.13.0-24-generic x86_64
  ApportVersion: 2.14.1-0ubuntu3
  Architecture: amd64
  Date: Mon Apr 21 15:29:28 2014
  SourcePackage: btrfs-tools
  UpgradeStatus: Upgraded to trusty on 2014-03-21 (30 days ago)

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