[Bug 610107] Re: Race condition at system-boot: md-RAID not always ready in time

[Gernot Hillier]

We also see somehow similar issues here sporadically on a number of
machines with 10.04.1 - in our case, we only have a data-RAID which is
not necessary for mounting root partition. And this data raid will stay
half-way assembled on some boots.

Currently, we think it's caused by udevd being killed in the middle of
its operation, see #613273.

If "mdadm --incremental" is interrupted at the wrong moment, it seems to
cause a lot of weird issues - ranging from a leftover /dev/.tmp.md.8:xx
which makes mdadm bailing out with "Strange error loading metadata for
/dev/md0" for all future operations until reboot to completely damaged
data structures in the kernel with wrong device numbers, half-busy
devices and the like.

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Title:
  Race condition at system-boot: md-RAID not always ready in time

Status in “udev” package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: udev

  Almost each time I start the System I get error-messages concerning my
  md-RAID devices.

  Example: 
  "udevd-work[77]: inotify_add_watch(6, /dev/md1, 10) failed: No such file or directory"

  Sometimes only one of my several RAIDs is concerned, sometimes more of them. 
  If this error shows up for the RAID my root directory is located on, the system won't boot but drop to a shell. 
  If only data-drives are concerned, the system finishes the boot process normally and all RAID drives are up by then.

  There are no remarkable entries in the log.

  The problem occurs on all three Lucid Installations I have made so
  far. (One was an upgrade from Karmic, the next was a fresh install,
  both on real hardware. The third is the one this report is done with,
  and this is a fresh Installation in a VirtualBox)

  /etc/mdadm/mdadm.conf:
  # definitions of existing MD arrays
  ARRAY /dev/md0 level=raid1 num-devices=2 metadata=0.90 UUID=cd601f2c:76c2a84f:2d20de61:3cd29610
  ARRAY /dev/md1 level=raid1 num-devices=2 metadata=0.90 UUID=5057c6bb:a8f652b9:2d20de61:3cd29610

  blkid:
  /dev/sda1: UUID="712d6c10-d9a5-4471-83b8-1e1f2749f817" TYPE="ext4" 
  /dev/sda5: UUID="696c8371-1612-4654-ac21-a7b08b35c950" TYPE="swap" 
  /dev/sdb1: UUID="cd601f2c-76c2-a84f-2d20-de613cd29610" TYPE="linux_raid_member" 
  /dev/sdc1: UUID="cd601f2c-76c2-a84f-2d20-de613cd29610" TYPE="linux_raid_member" 
  /dev/sdd1: UUID="5057c6bb-a8f6-52b9-2d20-de613cd29610" TYPE="linux_raid_member" 
  /dev/sde1: UUID="5057c6bb-a8f6-52b9-2d20-de613cd29610" TYPE="linux_raid_member" 
  /dev/md1: UUID="tM2vUv-zY1H-i1LW-wlDb-3qit-23uE-33fxP6" TYPE="LVM2_member" 
  /dev/md0: UUID="5MJTwi-LIkA-oxV4-328f-nqD6-nev6-fFzRHD" TYPE="LVM2_member" 
  /dev/mapper/vg1-test: UUID="de6e51c6-4cce-4810-9cb9-47d1a730ca6d" TYPE="jfs" 

  Ubuntu-Release: 
  Description:	Ubuntu 10.04.1 LTS
  Release:	10.04

  ProblemType: Bug
  DistroRelease: Ubuntu 10.04
  Package: udev 151-12
  ProcVersionSignature: Ubuntu 2.6.32-24.38-generic 2.6.32.15+drm33.5
  Uname: Linux 2.6.32-24-generic i686
  Architecture: i386
  CustomUdevRuleFiles: 70-xorg-vboxmouse.rules 60-vboxadd.rules
  Date: Mon Jul 26 16:18:20 2010
  InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Beta i386 (20100318)
  Lsusb: Error: command ['lsusb'] failed with exit code 1:
  MachineType: innotek GmbH VirtualBox
  ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-24-generic root=UUID=712d6c10-d9a5-4471-83b8-1e1f2749f817 ro quiet splash
  ProcEnviron:
   LANG=de_DE.utf8
   SHELL=/bin/bash
  SourcePackage: udev
  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

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