Hi Folks,
Greetings from Berlin.
We have a RAID5 (originally with 4 drives) - but it seems 1 drive has
failed although it still appears in lsscsi.
Of the remaining 3 drives, 2 have the correct Event that matches the
Array Event.
My question is: what is the best way to get the array to a readable
state? Do we need to replace the failed drive or should we be able to
recover with the remaining 3 drives?
Here is some more info:
At boot we have messages like the following:
raid5 failed to run raid set md0
....
mdadm: failed to RUN_ARRAY
......
could not bd_claim sda2
......
md0 already running, cannot run sdb2
.......
here is our mdadm.conf:
cat /etc/mdadm.conf
/dev/md0 <- the raid
/dev/sda2 <- the raid members.
/dev/sdb2
/dev/sdc2
/dev/sdd2
and our mdstat:
cat /proc/mdstat
Personalities : [raid5]
md0 : inactive sda2[0] sdd2[3] sdc2[2]
a-number blocks
unused devices <none>
Thus it seems we are missing sdb2[1] from the array.
mdadm --detail /dev/md0
Device Site: 288.47 GB
Raid Devices: 4
Total Devices: 3
Preferred Minor : 0
Persistance: Superblock is persistent
Update Time: Jun 1 2004 (note: system date is june 17 2007)
State: active, degraded
Active devices: 3
Working devices: 3
Failed Devices: 0
Spare Devices: 0
Layout: left-symetric
Chunk Size: 128K
UUID: a-long-char-string.
Events: 0.35025133
Number Major Minor RaidDevice State
0 8 2 0 active sync /dev/sda2
1 0 0 - removed
2 8 34 2 active sync /dev/sdc2
3 8 50 3 active sync /dev/sdd2
------------------
It seems that the array is both dirty and degraded. Only two of the drives have the same "Event"
and one would hope that at least 3 (in a 4 drive array) would have the same "Event" number.
Guess this is the number of operations on each drive since they (all) joined the raid.
this is discovered thus:
mdadm -E /dev/sd[b-i]1 | grep Event
Events : 0.32012979 <- different!
Events : 0.35025133
Events : 0.35025133
However, lsscsi shows all 4 drives (as ATA drives)
Any suggestions much appreciated!
cheers,
Simon.
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