[Bug 136252] Re: [->UUIDudev] mdadm.conf w/o ARRAY lines but udev/mdadm not assembling arrays. (boot & hotplug fails)

[Tor Henning Ueland]

I can also confirm that this bug is stil present on precise

I first did a release-upgrade when the crash started appearing. I
reinstalled the box and the issue still appears. I will try these tips
here regarding mdadm.conf.

On a related note. I find it interesting that my only RAID-device
becomes /dev/md127 instead of /dev/md0 as it has always been.


root at dom0:/home/thu# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=12.04
DISTRIB_CODENAME=precise
DISTRIB_DESCRIPTION="Ubuntu 12.04 LTS"




root at dom0:/home/thu# cat /etc/mdadm/mdadm.conf
# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#

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

# 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

# This file was auto-generated on Sat, 28 Jul 2012 01:05:22 +0200
# by mkconf $Id$



root at dom0:/home/thu# mdadm --detail /dev/md127
/dev/md127:
        Version : 0.90
  Creation Time : Sat Jan 24 14:16:52 2009
     Raid Level : raid6
     Array Size : 13186245888 (12575.38 GiB 13502.72 GB)
  Used Dev Size : 1465138432 (1397.26 GiB 1500.30 GB)
   Raid Devices : 11
  Total Devices : 12
Preferred Minor : 127
    Persistence : Superblock is persistent

    Update Time : Sat Jul 28 13:31:06 2012
          State : clean, degraded, recovering
 Active Devices : 10
Working Devices : 11
 Failed Devices : 1
  Spare Devices : 1

         Layout : left-symmetric
     Chunk Size : 128K

 Rebuild Status : 85% complete

           UUID : 1f095377:1c62a5f4:352a6ad4:582f9bd3
         Events : 0.608892

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https://bugs.launchpad.net/bugs/136252

Title:
  [->UUIDudev]  mdadm.conf w/o ARRAY lines but udev/mdadm not assembling
  arrays. (boot & hotplug fails)

Status in “mdadm” package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: mdadm

  Hi,

  I could not boot from my /dev/md1 -> /dev/vg01/lv_root partition,
  because the initrd could not assemble the md0 and md1 devices. After
  reading mdadm.conf, I added these two lines to my config:

  # definitions of existing MD arrays
  ARRAY /dev/md0 devices=/dev/sda1,/dev/sdb1
  ARRAY /dev/md1 devices=/dev/sda5,/dev/sdb5

  and updated initramfs. After this, the system started normally. Before
  figuring out this, I used dpkg-reconfigure mdadm. So this seems to
  produce a non working config, which is copied to the initrd.

  Kind regards

  Christian

  -> However on hotplug systems mdadm.conf should not have to contain
  any references to specific DEVICEs, ARRAYs or HOMEHOST.

  -> We need to switch to a pure and secure UUID-based raid assembly.
  The boot up scripts already support and use UUIDs, but mdadm needs to
  be convinced (-> comment #42)

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