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Raid 5 Array Failed
My server at home operates a 4 disk software RAID 5 array which is normally mounted at /.
At the moment I am using mdadm v2.6.7.2 (I don't know which version built the array).
One of the disks appeared to have developed a fault, an I/O error would be produced and the array would rebuild to try and mao round it, and once it had finished there'd be another I/O error and it would start again.
I marked the drive as faulty, removed it from the array, replaced it with a nother drive, replicated the partition map and added it to the array.
As expected the drive started being built.
I'm not sure if it had finished by this point, but another disk produced an I/O error which broke the array.
Now I'm trying to recover any data I can from it.
The partitions in the array are sd[abcd]1. (SATA controller).
sdb is the drive that originally failed and has been replaced. sdc is the drive that took everything down.
When I first try to assemble the array, this message appears in kernel messages.
md: kicking non-fresh sdc1 from array!
and this appears in the console.
mdadm: /dev/md0 assembled from 2 drives and 1 spare - not enough to start the array.
even if I use --force.
with this in mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : inactive sdd1[2](S) sdc1[1](S) sdb1[5](S) sda1[4](S)
1937888128 blocks super 1.0
unused devices: <none>
(well, all the [S], except the one on sdb1 appearing is new).
If I try to fail and remove sdc1 and then reinsert it I get.
mdadm /dev/md0 -f /dev/sdc1
mdadm: cannot get array info for /dev/md0
I get the same if I try to:
mdadm --detail /dev/md0
from examine I get
/dev/sda1:
Magic : a92b4efc
Version : 1.0
Feature Map : 0x0
Array UUID : 62f0dee0:e3a81d0c:68df2ad8:1ecb435b
Name : 'chef':1
Creation Time : Mon Jul 21 15:58:36 2008
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 968944072 (462.03 GiB 496.10 GB)
Array Size : 2906832000 (1386.09 GiB 1488.30 GB)
Used Dev Size : 968944000 (462.03 GiB 496.10 GB)
Super Offset : 968944328 sectors
State : clean
Device UUID : 0bf37dbc:000ee685:7bcf601b:ff125af1
Update Time : Fri Jul 10 18:45:04 2009
Checksum : ef734a25 - correct
Events : 19518
Layout : left-symmetric
Chunk Size : 64K
Array Slot : 4 (failed, failed, 2, failed, 3)
Array State : __uU 3 failed
/dev/sdb1:
Magic : a92b4efc
Version : 1.0
Feature Map : 0x0
Array UUID : 62f0dee0:e3a81d0c:68df2ad8:1ecb435b
Name : 'chef':1
Creation Time : Mon Jul 21 15:58:36 2008
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 968944200 (462.03 GiB 496.10 GB)
Array Size : 2906832000 (1386.09 GiB 1488.30 GB)
Used Dev Size : 968944000 (462.03 GiB 496.10 GB)
Super Offset : 968944328 sectors
State : clean
Device UUID : bb71f618:9d9be6e2:84bd3fdb:02543dfb
Update Time : Fri Jul 10 18:45:04 2009
Checksum : 72ae8ca8 - correct
Events : 19518
Layout : left-symmetric
Chunk Size : 64K
Array Slot : 5 (failed, failed, 2, failed, 3)
Array State : __uu 3 failed
/dev/sdc1:
Magic : a92b4efc
Version : 1.0
Feature Map : 0x0
Array UUID : 62f0dee0:e3a81d0c:68df2ad8:1ecb435b
Name : 'chef':1
Creation Time : Mon Jul 21 15:58:36 2008
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 968944200 (462.03 GiB 496.10 GB)
Array Size : 2906832000 (1386.09 GiB 1488.30 GB)
Used Dev Size : 968944000 (462.03 GiB 496.10 GB)
Super Offset : 968944328 sectors
State : clean
Device UUID : 0259688e:21902f87:a4da25cd:a5042e6f
Update Time : Fri Jul 10 18:45:04 2009
Checksum : f2402efa - correct
Events : 19375
Layout : left-symmetric
Chunk Size : 64K
Array Slot : 1 (failed, failed, 2, failed, 3)
Array State : __uu 3 failed
/dev/sdd1:
Magic : a92b4efc
Version : 1.0
Feature Map : 0x0
Array UUID : 62f0dee0:e3a81d0c:68df2ad8:1ecb435b
Name : 'chef':1
Creation Time : Mon Jul 21 15:58:36 2008
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 968944072 (462.03 GiB 496.10 GB)
Array Size : 2906832000 (1386.09 GiB 1488.30 GB)
Used Dev Size : 968944000 (462.03 GiB 496.10 GB)
Super Offset : 968944328 sectors
State : clean
Device UUID : 1f3b1479:3e01d8dd:d8ce565a:cb13e780
Update Time : Fri Jul 10 18:45:04 2009
Checksum : d27e859e - correct
Events : 19518
Layout : left-symmetric
Chunk Size : 64K
Array Slot : 2 (failed, failed, 2, failed, 3)
Array State : __Uu 3 failed
As you can see sdc1's event count is more than a little out, oddly sdb1 is in State: clean.
I've run out of ideas, can somoneone please give me a point in the right direction as to how to recover some of the data from this.
TIA for any help received.
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