[Bug 964052] Re: mdadm: created as /dev/md0, becomes /dev/md127 after reboot.

[Jason Wagner]

Reinstalling from the same ISO, I used guided partitioning to completely
wipe the root partition and reinstall the system.  At the same time, I
also told it to mount the array.

After installation, my array is mounted and I see this in /etc/fstab:

# /media/raid was on /dev/md0 during installation
UUID=c3cc60a8-e441-4c68-a59d-ee6bacaf1e34 /media/raid     ext4    defaults        0       2

Sure enough, the array is now assembled as /dev/md0.  Of course, I
shouldn't have to do that when I told mdadm that I wanted the array to
be /dev/md0 in the first place.

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Title:
  mdadm: created as /dev/md0, becomes /dev/md127 after reboot.

Status in “mdadm” package in Ubuntu:
  New

Bug description:
  -- lsb_release -rd
  Description:    Ubuntu precise (development branch)
  Release:        12.04
  --

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

  -- Environment
  Ubuntu 12.04 Server Edition 64bit (installed from the 20120323 daily ISO)
  Installed into a guest running on VirtualBox 4.1.10, hosted on Windows 7.
  Disk configuration: 
  1 SATA controller
  1 20GB HDD (used at / mount point)
  5x 512MB HDD (used to simulate RAID5 array)
  --

  -- What action I took
  On an untouched installation, I install mdadm, and attempt to create a RAID5 array with this command:

  sudo mdadm --create /dev/md0 --level=5 --raid-devices=5 /dev/sdb
  /dev/sdc /dev/sdd /dev/sde /dev/sdf

  After confirming that I wanted to create the array, mdadm reported success.  I initialized a file system on it, mounted it, and created a simple text file containing 'Hello World' on it.  Then, I reboot.
  --

  -- What I expected to happen
  mdadm would reassemble the array at boot time as /dev/md0.
  --

  -- What happened instead
  mdadm reassemled the array at boot time as /dev/md127.
  --

  It took a great deal if hunting around to discover that the array had
  actually been assembled.  I forget what command I issued that finally
  tipped me off to the existence of the assembled array, but running
  'sudo mdadm --detail /dev/md127' confirmed that it was the array I had
  just built.  I mounted the array and viewed the contents of the text
  file to confirm.

  This did not occur when I built my array on my test and production
  servers running Ubuntu 10.04 Server 64bit, so I am calling this new
  and unexpected behavior, and filing it as a bug.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: mdadm 3.2.3-2ubuntu1
  ProcVersionSignature: Ubuntu 3.2.0-20.32-generic 3.2.12
  Uname: Linux 3.2.0-20-generic x86_64
  ApportVersion: 1.95-0ubuntu1
  Architecture: amd64
  CurrentDmesg:
   
  Date: Sat Mar 24 11:05:07 2012
  InstallationMedia: Ubuntu-Server 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120323)
  MDadmExamine.dev.sda: Error: command ['/sbin/mdadm', '-E', '/dev/sda'] failed with exit code 1: mdadm: cannot open /dev/sda: Permission denied
  MDadmExamine.dev.sda1: Error: command ['/sbin/mdadm', '-E', '/dev/sda1'] failed with exit code 1: mdadm: cannot open /dev/sda1: Permission denied
  MDadmExamine.dev.sda2: Error: command ['/sbin/mdadm', '-E', '/dev/sda2'] failed with exit code 1: mdadm: cannot open /dev/sda2: Permission denied
  MDadmExamine.dev.sda5: Error: command ['/sbin/mdadm', '-E', '/dev/sda5'] failed with exit code 1: mdadm: cannot open /dev/sda5: Permission denied
  MDadmExamine.dev.sdb: Error: command ['/sbin/mdadm', '-E', '/dev/sdb'] failed with exit code 1: mdadm: cannot open /dev/sdb: Permission denied
  MDadmExamine.dev.sdc: Error: command ['/sbin/mdadm', '-E', '/dev/sdc'] failed with exit code 1: mdadm: cannot open /dev/sdc: Permission denied
  MDadmExamine.dev.sdd: Error: command ['/sbin/mdadm', '-E', '/dev/sdd'] failed with exit code 1: mdadm: cannot open /dev/sdd: Permission denied
  MDadmExamine.dev.sde: Error: command ['/sbin/mdadm', '-E', '/dev/sde'] failed with exit code 1: mdadm: cannot open /dev/sde: Permission denied
  MDadmExamine.dev.sdf: Error: command ['/sbin/mdadm', '-E', '/dev/sdf'] failed with exit code 1: mdadm: cannot open /dev/sdf: Permission denied
  MachineType: innotek GmbH VirtualBox
  ProcEnviron:
   TERM=xterm
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.2.0-20-generic root=/dev/mapper/hostname-root ro
  SourcePackage: mdadm
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 12/01/2006
  dmi.bios.vendor: innotek GmbH
  dmi.bios.version: VirtualBox
  dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:
  dmi.product.name: VirtualBox
  dmi.product.version: 1.2
  dmi.sys.vendor: innotek GmbH
  etc.blkid.tab: Error: [Errno 2] No such file or directory: '/etc/blkid.tab'

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