[Bug 332235] Re: RAID5 partitions disappear after initial reboot [old superblocks]

[Launchpad Bug Tracker]

[Expired for mdadm (Ubuntu) because there has been no activity for 60
days.]

** Changed in: mdadm (Ubuntu)
       Status: Incomplete => Expired

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Title:
  RAID5 partitions disappear after initial reboot [old superblocks]

Status in “mdadm” package in Ubuntu:
  Expired

Bug description:
  Binary package hint: mdadm

  My 3-disk RAID5 array was build in Ubuntu 8.04, and worked great for
  many months. It uses full-disk partions sdb1, sdc1, and sde1. I wiped
  my (non-RAID) "/" partition in order to install Ubuntu 8.10. After the
  initial install of mdadm in 8.10 (without any reboot), all 3 of those
  partitions show up in dev, and I can use them to assemble my array,
  which then mounts without difficulty:

  [CODE]
  # mdadm --detail /dev/md0
  /dev/md0:
          Version : 00.90
    Creation Time : Wed Apr  2 16:21:23 2008
       Raid Level : raid5
       Array Size : 1465143808 (1397.27 GiB 1500.31 GB)
    Used Dev Size : 732571904 (698.64 GiB 750.15 GB)
     Raid Devices : 3
    Total Devices : 3
  Preferred Minor : 0
      Persistence : Superblock is persistent

      Update Time : Fri Feb 20 13:58:32 2009
            State : clean
   Active Devices : 3
  Working Devices : 3
   Failed Devices : 0
    Spare Devices : 0

           Layout : left-symmetric
       Chunk Size : 64K

             UUID : dbdec02d:c53e6535:80dcd6ba:f1e671fb
           Events : 0.5962

      Number   Major   Minor   RaidDevice State
         0       8       17        0      active sync   /dev/sdb1
         1       8       33        1      active sync   /dev/sdc1
         2       8       65        2      active sync   /dev/sde1

  # cat /etc/mdadm/mdadm.conf
  # mdadm.conf
  #
  # Please refer to mdadm.conf(5) for information about this file.
  #

  # by default, scan all partitions (/proc/partitions) for MD superblocks.
  # alternatively, specify devices to scan, using wildcards if desired.
  DEVICE partitions

  # auto-create devices with Debian standard permissions
  CREATE owner=root group=disk mode=0660 auto=yes

  # automatically tag new arrays as belonging to the local system
  HOMEHOST <system>

  # instruct the monitoring daemon where to send mail alerts
  MAILADDR root

  # definitions of existing MD arrays
  ARRAY /dev/md0 level=raid5 num-devices=3 UUID=28ce99d8:12dc7f14:80dcd6ba:f1e671fb
  ARRAY /dev/md0 level=raid5 num-devices=3 UUID=dbdec02d:c53e6535:80dcd6ba:f1e671fb

  # This file was auto-generated on Fri, 20 Feb 2009 13:57:25 -0500
  # by mkconf $Id$
  [/CODE]

  However, as soon as I reboot my computer, sdb1 sdc1 and sde1 no longer
  exist, although fdisk still sees them on the disks. Trying to assemble
  the array causes it to build a degraded array out of sdb and sdc
  (without using the partitions, just using the disks directly), but
  this array will not mount (system does not see a valid ext3 partition
  on there):

  [CODE]
  # cat /etc/mdadm/mdadm.conf
  # mdadm.conf
  #
  # Please refer to mdadm.conf(5) for information about this file.
  #

  # by default, scan all partitions (/proc/partitions) for MD superblocks.
  # alternatively, specify devices to scan, using wildcards if desired.
  DEVICE partitions

  # auto-create devices with Debian standard permissions
  CREATE owner=root group=disk mode=0660 auto=yes

  # automatically tag new arrays as belonging to the local system
  HOMEHOST <system>

  # instruct the monitoring daemon where to send mail alerts
  MAILADDR root

  # definitions of existing MD arrays
  ARRAY /dev/md0 level=raid5 num-devices=3 UUID=28ce99d8:12dc7f14:80dcd6ba:f1e671fb
  ARRAY /dev/md0 level=raid5 num-devices=3 UUID=dbdec02d:c53e6535:80dcd6ba:f1e671fb

  # This file was auto-generated on Fri, 20 Feb 2009 13:57:25 -0500
  # by mkconf $Id$

  # mdadm --detail /dev/md0
  /dev/md0:
          Version : 00.90
    Creation Time : Wed Apr  2 16:08:44 2008
       Raid Level : raid5
       Array Size : 1465148928 (1397.27 GiB 1500.31 GB)
    Used Dev Size : 732574464 (698.64 GiB 750.16 GB)
     Raid Devices : 3
    Total Devices : 2
  Preferred Minor : 0
      Persistence : Superblock is persistent

      Update Time : Fri Feb 20 14:02:49 2009
            State : clean, degraded
   Active Devices : 2
  Working Devices : 2
   Failed Devices : 0
    Spare Devices : 0

           Layout : left-symmetric
       Chunk Size : 64K

             UUID : 28ce99d8:12dc7f14:80dcd6ba:f1e671fb
           Events : 0.34

      Number   Major   Minor   RaidDevice State
         0       8       16        0      active sync   /dev/sdb
         1       8       32        1      active sync   /dev/sdc
         2       0        0        2      removed
  [/CODE]

  The only way to get the partitions sdb1 sdc1 and sde1 to appear in the
  filesystem again is to remove mdadm. After doing so and rebooting, the
  partitions will again exist, and if I again install mdadm (without a
  reboot), I can assemble the full array and mount it, until the next
  reboot.

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