Raid0 not starting after reboot

[mjo_se]

Hi.

I month ago I created a raid0 of two partitions. The command I used was
root@rt:~# mdadm -Cv /dev/md1 -l0 -n2 -c128 /dev/sde4 /dev/sdf2
However, I did not save the configuration into /etc/mdadm/mdadm.conf and I think this is the reason the array does not start after my reboot.

Some info:

root@rt:~# fdisk -l /dev/sdf

Disk /dev/sdf: 200.0 GB, 200049647616 bytes
255 heads, 63 sectors/track, 24321 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x4a44301f

Device Boot Start End Blocks Id System
/dev/sdf1 1 2980 23936818+ 83 Linux
/dev/sdf2 2981 24321 171421582+ 83 Linux

root@rt:~# fdisk -l /dev/sde

Disk /dev/sde: 200.0 GB, 200049647616 bytes
255 heads, 63 sectors/track, 24321 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x23e923e9

Device Boot Start End Blocks Id System
/dev/sde1 * 1 62 497983+ 83 Linux
/dev/sde2 63 548 3903795 82 Linux swap / Solaris
/dev/sde3 549 2980 19535040 83 Linux
/dev/sde4 2981 24321 171421582+ 83 Linux

root@rt:~# mdadm --examine /dev/sde4
mdadm: No md superblock detected on /dev/sde4.

root@rt:~# mdadm --examine /dev/sdf2
/dev/sdf2:
Magic : a92b4efc
Version : 00.90.00
UUID : cf2c6121:10be48da:d7c001fd:1f6c6f91 (local to host rt)
Creation Time : Sun Jul 6 20:59:08 2008
Raid Level : raid0
Used Dev Size : 0
Raid Devices : 2
Total Devices : 2
Preferred Minor : 1

Update Time : Sun Jul 6 20:59:08 2008
State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Checksum : 112697fa - correct
Events : 0.1

Chunk Size : 128K

Number Major Minor RaidDevice State
this 1 8 82 1 active sync /dev/sdf2

0 0 8 68 0 active sync
1 1 8 82 1 active sync /dev/sdf2

I am a bit worried by the output of examination of sde4, but I am not sure what it means.

I do not have any essential data on this array that has not been backed up (it is a raid0 after all), but I would prefer to restart the array instead of restoring things from a backup.

Any ideas on how I should proceed?

[siDDis]

Maybe this thread can help you

http://ubuntuforums.org/showthread.php?t=854528

[mjo_se]

Thanks a lot for the reply siDDis

I tried the solution described in the thread, but got this:

root@rt:~# mdadm --assemble --run --force --verbose /dev/md1 /dev/sde4 /dev/sdf2
mdadm: looking for devices for /dev/md1
mdadm: no recogniseable superblock on /dev/sde4
mdadm: /dev/sde4 has no superblock - assembly aborted

Looks like the missing superblock on sde4 is a problem.
I also tried to recreate the array:

root@rt:~# mdadm -Cv /dev/md1 -l0 -n2 -c128 --verbose /dev/sde4 /dev/sdf2
mdadm: /dev/sde4 is too small: 0K
mdadm: /dev/sdf2 appears to be part of a raid array:
level=raid0 devices=2 ctime=Sun Jul 6 20:59:08 2008
mdadm: create aborted

[mjo_se]

ok, there is definitely something wrong with sde4:

root@rt:~# dd if=/dev/sde4 of=/mnt/storage/sde4_backup count=40
0+0 records in
0+0 records out
0 bytes (0 B) copied, 2.2877e-05 s, 0.0 kB/s


Other partitions on this disk are fine. I have / and swap here so I would have noticed :-)

[mjo_se]

My guess is that the kernel read the partition table wrong or something. Anyway, I rebooted and now the array works like a charm.