[Bug 1164008] Re: mdadm devices not recognized correctly at boot

[Austin Brashear]

I'm digging into this some more and it seems that mdadm in Ubuntu 12.04
is detecting an old unused superblock on /dev/sdb that mdadm in Ubuntu
10.04 ignored.

$ mdadm --examine --scan --verbose
ARRAY /dev/md1 level=raid1 num-devices=2 UUID=5fb6928e:89f09cde:d0aebb6f:e3c24c31
   spares=1   devices=/dev/sdb
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=a4176cee:096f0ba6:40663db4:2b8b6d2c
   devices=/dev/sdc1,/dev/sdb1

When we examine /dev/sdb, we see there's an old superblock there (note
the update date is Thu Jul  7 09:00:21 2011).

$ mdadm --examine /dev/sdb
/dev/sdb:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : 5fb6928e:89f09cde:d0aebb6f:e3c24c31
  Creation Time : Fri Jul  1 10:00:58 2011
     Raid Level : raid1
  Used Dev Size : 1953513408 (1863.02 GiB 2000.40 GB)
     Array Size : 1953513408 (1863.02 GiB 2000.40 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 1

    Update Time : Thu Jul  7 09:00:21 2011
          State : clean
 Active Devices : 1
Working Devices : 2
 Failed Devices : 1
  Spare Devices : 1
       Checksum : 57d747d3 - correct
         Events : 24


      Number   Major   Minor   RaidDevice State
this     2       8       16        2      spare   /dev/sdb

   0     0       8       33        0      active sync   /dev/sdc1
   1     1       0        0        1      faulty removed
   2     2       8       16        2      spare   /dev/sdb

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Title:
  mdadm devices not recognized correctly at boot

Status in “mdadm” package in Ubuntu:
  New

Bug description:
  I just upgraded a working 10.04 LTS server to 12.04 LTS. The server
  has two non-boot drives in a software RAID1 configuration. This array
  worked fine in 10.04 LTS.

  When the machine boots I should get one active array, /dev/md0
  consisting of /dev/sdb1 and /dev/sdc1. Instead, I get dumped to a
  busybox session and after quitting that and booting I get two inactive
  arrays: md0 (consisting of /dev/sdc1 as spare) and md127 (consisting
  of /dev/sdb as spare). If I run mdadm --detail /dev/md0 or mdadm
  --detail /dev/md127 I get that the device does not appear to be
  active.

  Once I've finished booting, I can assemble my array manually by
  running mdadm --stop /dev/md0 and mdadm --stop /dev/md127 and then
  assembling the array with mdadm --assemble /dev/md0 /dev/sdb1
  /dev/sdc1.

  Below are the results of some troubleshooting:
  $ lsb_release -rd
  Description:    Ubuntu 12.04.2 LTS
  Release:        12.04


  $ apt-cache policy mdadm
  mdadm:
    Installed: 3.2.5-1ubuntu0.2
    Candidate: 3.2.5-1ubuntu0.2
    Version table:
   *** 3.2.5-1ubuntu0.2 0
          500 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       3.2.3-2ubuntu1 0
          500 http://us.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages


  $ cat /proc/mdstat
  Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
  md0 : inactive sdc1[1](S)
        1953513408 blocks

  md127 : inactive sdb[2](S)
        1953514496 blocks

  unused devices: <none>


  $ mdadm --examine /dev/sdb1
  /dev/sdb1:
            Magic : a92b4efc
          Version : 0.90.00
             UUID : a4176cee:096f0ba6:40663db4:2b8b6d2c
    Creation Time : Thu Jul  7 09:32:01 2011
       Raid Level : raid1
    Used Dev Size : 1953513408 (1863.02 GiB 2000.40 GB)
       Array Size : 1953513408 (1863.02 GiB 2000.40 GB)
     Raid Devices : 2
    Total Devices : 2
  Preferred Minor : 0

      Update Time : Wed Apr  3 10:32:36 2013
            State : clean
   Active Devices : 2
  Working Devices : 2
   Failed Devices : 0
    Spare Devices : 0
         Checksum : d685ab7e - correct
           Events : 722

  
        Number   Major   Minor   RaidDevice State
  this     0       8       17        0      active sync   /dev/sdb1

     0     0       8       17        0      active sync   /dev/sdb1
     1     1       8       33        1      active sync   /dev/sdc1


  
  $ mdadm --examine /dev/sdc1
  /dev/sdc1:
            Magic : a92b4efc
          Version : 0.90.00
             UUID : a4176cee:096f0ba6:40663db4:2b8b6d2c
    Creation Time : Thu Jul  7 09:32:01 2011
       Raid Level : raid1
    Used Dev Size : 1953513408 (1863.02 GiB 2000.40 GB)
       Array Size : 1953513408 (1863.02 GiB 2000.40 GB)
     Raid Devices : 2
    Total Devices : 2
  Preferred Minor : 0

      Update Time : Wed Apr  3 10:32:36 2013
            State : clean
   Active Devices : 2
  Working Devices : 2
   Failed Devices : 0
    Spare Devices : 0
         Checksum : d685ab90 - correct
           Events : 722

  
        Number   Major   Minor   RaidDevice State
  this     1       8       33        1      active sync   /dev/sdc1

     0     0       8       17        0      active sync   /dev/sdb1
     1     1       8       33        1      active sync   /dev/sdc1

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