mdadm configures device enumeration (not UUID)

[Louis]

Binary package hint: mdadm

I configured software RAID on my PC (not the boot partition or drive) as per http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch26_:_Linux_Software_RAID#Sponsors.

On reboot, the RAID device created (/dev/md0) is gone.

On each boot, my drives come up with different device enumeration (not so unusual). The pair I have assigned to RAID1 seem to alternate between /dev/sda,/dev/sdb and /dev/sdd,/dev/sde. After speaking with someone on the Ubuntu Freenode IRC channel, I am under the impression mdadm should use UUID, so /dev juggling shouldn't be an issue. I was told that this was outside normal behavior for mdadm and to file as a bug.

My /etc/mdadm.conf file contains:
ARRAY /dev/md0 level=raid1 num-devices=2 metadata=00.90 UUID=1ba93afc:fa814389:391f4b2c:490e7fce
   devices=/dev/sdd1,/dev/sde1

I am new to software RAID, so please let me know what other debugging information I can provide.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: mdadm 2.6.7.1-1ubuntu15
ProcVersionSignature: Ubuntu 2.6.32-23.37-generic 2.6.32.15+drm33.5
Uname: Linux 2.6.32-23-generic i686
Architecture: i386
Date: Tue Jul 13 19:17:13 2010
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
MDadmExamine.dev.sda:
 Error: command ['/sbin/mdadm', '-E', '/dev/sda'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sda.
MDadmExamine.dev.sda1:
 Error: command ['/sbin/mdadm', '-E', '/dev/sda1'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sda1.
MDadmExamine.dev.sdb:
 Error: command ['/sbin/mdadm', '-E', '/dev/sdb'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sdb.
MDadmExamine.dev.sdb1:
 Error: command ['/sbin/mdadm', '-E', '/dev/sdb1'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sdb1.
MDadmExamine.dev.sdb2:
 Error: command ['/sbin/mdadm', '-E', '/dev/sdb2'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sdb2.
MDadmExamine.dev.sdb5:
 Error: command ['/sbin/mdadm', '-E', '/dev/sdb5'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sdb5.
MDadmExamine.dev.sdc:
 Error: command ['/sbin/mdadm', '-E', '/dev/sdc'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sdc.
MDadmExamine.dev.sdc1:
 Error: command ['/sbin/mdadm', '-E', '/dev/sdc1'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sdc1.
MDadmExamine.dev.sdd:
 Error: command ['/sbin/mdadm', '-E', '/dev/sdd'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sdd.
MDadmExamine.dev.sde:
 Error: command ['/sbin/mdadm', '-E', '/dev/sde'] failed with exit code 1: mdadm: metadata format 00.90 unknown, ignored.
 mdadm: No md superblock detected on /dev/sde.
MachineType: System manufacturer System Product Name
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-23-generic root=UUID=06930178-ffb9-4b9f-a078-d58a8a2fe733 ro quiet splash
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.utf8
 SHELL=/bin/bash
ProcMDstat:
 Personalities :
 unused devices: <none>
SourcePackage: mdadm
dmi.bios.date: 03/31/2010
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1015
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: M4A88TD-V EVO/USB3
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1015:bd03/31/2010:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnM4A88TD-VEVO/USB3:rvrRevX.0x:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: System Product Name
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer
etc.blkid.tab: Error: [Errno 2] No such file or directory: '/etc/blkid.tab'
initrd.files:

[ceg (ceg)]

See https://wiki.ubuntu.com/ReliableRaid
and the bugs with [->UUIDudev].

You may well find the reason and workaround of your md devices that are gone after reboot in one of the other bugs filed against the mdadm package that is distributed with ubuntu, but has not seen any maintenance for years.

[Sergei Vorobyov (svorobyov)]

Confirmed, same kind of behavior on my Ubuntu 10.04.

In good old days raids survived even complete system reinstallations and migrations to different distributions.

In Ubuntu they don't even survive reboots.

See:

https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/601305