Software RAID not working after upgrade to 11.04

[vitke]

Hi all

I upgraded from 10.10 to 11.04, and now I cannot mount my raid drive. At the boot time I'm getting the message that the drive cannot be mounted, and I choose to skip it. Then I try to mount it from the command line, but I'm getting


mount: wrong fs type, bad option, bad superblock on /dev/md0,
missing codepage or helper program, or other error
(could this be the IDE device where you in fact use
ide-scsi so that sr0 or sda or so is needed?)
In some cases useful info is found in syslog - try
dmesg | tail or so

cat /proc/mdstat gives

Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : inactive sdb[1](S)
1465138496 blocks

mdadm --examine /dev/sda gives

mdadm: No md superblock detected on /dev/sda.

and /dev/sdb seems to be fine because mdadm --examine /dev/sdb gives

/dev/sdb:
Magic : a92b4efc
Version : 0.90.00
UUID : 93d55dae:ba268f09:9c0f36fb:5e8cac09 (local to host yes)
Creation Time : Fri Jan 22 20:48:02 2010
Raid Level : raid1
Used Dev Size : 1465138496 (1397.26 GiB 1500.30 GB)
Array Size : 1465138496 (1397.26 GiB 1500.30 GB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 0

Update Time : Thu May 5 22:00:34 2011
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Checksum : e27b25f8 - correct
Events : 2319164


Number Major Minor RaidDevice State
this 1 8 16 1 active sync /dev/sdb

0 0 8 0 0 active sync /dev/sda
1 1 8 16 1 active sync /dev/sdb

/etc/mdadm/mdadm.conf contains

DEVICE partitions
CREATE owner=root group=disk mode=0660 auto=yes
HOMEHOST <system>
MAILADDR root
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=93d55dae:ba268f09:9c0f36fb: 5e8cac09
devices=/dev/sda,/dev/sdb

So what could be wrong?

[vitke]

To answer my own question, the problem was that on each disk the file systems were larger than devices, and this was the case because something (me?) has created the file systems before adding superblocks at the end of the disks, if I understood correctly some link that I can't find now. So the file systems were supposed to be resized at the end (by something - me?), but they were not resized. It is an enigma how it worked so far, but after the upgrade it didn't work any more. So all I had to do was to run

sudo e2fsck -f /dev/sda
and answer 'n' when asked to quit, then

sudo resize2fs /dev/sda
and then all the same for /dev/sdb.

[vitke]

Well, not really... As a result, I can now mount both disks separately, but I cannot assemble /dev/md0. It says

mdadm: /dev/sda has no superblock - assembly aborted
So it seems that my resize command deleted the superblocks. How can I create them?