[Bug 1014848] Re: Systems sometimes come up with RAID devices dropped, re-adding fails.

[Iordan Iordanov]

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https://bugs.launchpad.net/bugs/1014848

Title:
  Systems sometimes come up with RAID devices dropped, re-adding fails.

Status in “mdadm” package in Ubuntu:
  New

Bug description:
  We have 3 systems with RAID1 sets which sometimes come up with one
  device missing. Attempting to re-add the device fails with:

  # mdadm /dev/md2 --re-add /dev/sda6
  mdadm: --re-add for /dev/sda6 to /dev/md2 is not possible

  # mdadm /dev/md2 --add /dev/sda6
  mdadm: /dev/sda6 reports being an active member for /dev/md2, but a --re-add fails.
  mdadm: not performing --add as that would convert /dev/sda6 in to a spare.
  mdadm: To make this a spare, use "mdadm --zero-superblock /dev/sda6" first.

  The only thing which "resolves" the problem is zeroing the superblock
  on the drive, and adding it to the RAID array. This causes an
  unnecessary rebuild of the drive, as it shouldn't have been dropped
  from the array in the first place.

  A similar, perhaps related problem occurred on a RAID6 system with 6
  devices. We failed/removed one device, and moved it to another slot on
  the system (probably irrelevant). Trying to add it back into the RAID6
  array resulted in the same error. This has happened with the newest
  kernel (3.2.0-25) as well as with 3.2.0-24 which was used to create
  this bug-report. It has also happened with different RAID levels,
  which is why I filed the bug against mdadm, rather than the kernel.

  A question with more details was posted by a colleague of mine here:
  https://answers.launchpad.net/ubuntu/+source/mdadm/+question/199471

  A question was posted by me in the linux-raid mailing list here:
  http://marc.info/?t=133953601900006&r=1&w=2

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: mdadm 3.2.3-2ubuntu1
  ProcVersionSignature: Ubuntu 3.2.0-24.39-generic-pae 3.2.16
  Uname: Linux 3.2.0-24-generic-pae i686
  ApportVersion: 2.0.1-0ubuntu8
  Architecture: i386
  Date: Mon Jun 18 17:12:16 2012
  Lsusb:
   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
   Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 001 Device 002: ID 04b4:6560 Cypress Semiconductor Corp. CY7C65640 USB-2.0 "TetraHub"
  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.sda6: Error: command ['/sbin/mdadm', '-E', '/dev/sda6'] failed with exit code 1: mdadm: cannot open /dev/sda6: Permission denied
  MDadmExamine.dev.sda7: Error: command ['/sbin/mdadm', '-E', '/dev/sda7'] failed with exit code 1: mdadm: cannot open /dev/sda7: Permission denied
  MDadmExamine.dev.sda8: Error: command ['/sbin/mdadm', '-E', '/dev/sda8'] failed with exit code 1: mdadm: cannot open /dev/sda8: Permission denied
  MDadmExamine.dev.sda9: Error: command ['/sbin/mdadm', '-E', '/dev/sda9'] failed with exit code 1: mdadm: cannot open /dev/sda9: 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.sdb1: Error: command ['/sbin/mdadm', '-E', '/dev/sdb1'] failed with exit code 1: mdadm: cannot open /dev/sdb1: Permission denied
  MachineType: Dell Computer Corporation PowerEdge 860
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   SHELL=/bin/bash
  ProcKernelCmdLine: root=/dev/sda1 ro
  ProcMDstat:
   Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
   md0 : active raid1 sda9[2] sdb1[0]
         409598840 blocks super 1.2 [2/2] [UU]
         
   unused devices: <none>
  SourcePackage: mdadm
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 04/04/2007
  dmi.bios.vendor: Dell Computer Corporation
  dmi.bios.version: A03
  dmi.board.name: 0XM089
  dmi.board.vendor: Dell Computer Corporation
  dmi.board.version: A00
  dmi.chassis.type: 23
  dmi.chassis.vendor: Dell Computer Corporation
  dmi.modalias: dmi:bvnDellComputerCorporation:bvrA03:bd04/04/2007:svnDellComputerCorporation:pnPowerEdge860:pvr:rvnDellComputerCorporation:rn0XM089:rvrA00:cvnDellComputerCorporation:ct23:cvr:
  dmi.product.name: PowerEdge 860
  dmi.sys.vendor: Dell Computer Corporation
  etc.blkid.tab:
   <device DEVNO="0x0801" TIME="1339993953.873769" UUID="153fb914-13c1-4ab2-9368-be196bbe589a" TYPE="ext4">/dev/sda1</device>
   <device DEVNO="0x0806" TIME="1339993967.110129" UUID="af709399-931c-4652-9565-5f53ccf8b5ce" TYPE="ext4">/dev/sda6</device>
   <device DEVNO="0x0900" TIME="1339994011.818058" UUID="e00278de-892f-4477-bf35-385af3725b28" TYPE="ext4">/dev/md0</device>

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