I have (had?) a 4-disk RAID5 array (/dev/md1), consisting of:
/dev/hda1
/dev/hdc1
/dev/hde1
/dev/hdg1
After some months of uptime, I had to reboot the system for a
non-related issue -- and when it came back up, the array was running
in degraded mode. After further investigating, I had found that it
did not auto-add /dev/hdc1 to the RAID5 array because I had forgotten
to set it's type to 0xFD. My bad.
I made up my mind to fix it, but didn't have the time at the moment
and so I shrugged, made a mental note of it, and re-added the drive to
the array manually with:
mdadm /dev/md1 -a /dev/hdc1
A `cat /proc/mdstat` showed me what I expected (that the array was
rebuilding), so I shrugged and went to do other things.
Some hours later, I returned to see that /dev/hdg1 had failed during
the rebuild process. Now I have a completely snarfed array, with two
drives that mdadm sees as clean (/dev/hda1 and /dev/hde1), a
could-be-mostly-rebuilt-but-still-partial drive (/dev/hdc1) and a
corrupted-but-who-knows-how-badly drive (/dev/hdg1).
I was considering retiring the machine anyway, to be replaced with
something newer... so right now I just want to save anything that I
can off of the machine. Is there any way for me to resurrect the
array and get some of my data off of it?
I tried the following, which I saw in the list archives:
mdadm -A /dev/md1 --uuid=a38910a6:51582805:6ccb5711:4ac501b2 --force
/dev/hdg1 /dev/hde1 /dev/hda1 /dev/hdc1
... but the response message was:
"mdadm: /dev/md1 assembled from 2 drives and 2 spares - not enough to
start the array."
Any help would be greatly appreciated.
mdadm --examine output for each of the involved partitions follows.
/dev/hdg1:
Magic : a92b4efc
Version : 00.90.00
UUID : a38910a6:51582805:6ccb5711:4ac501b2
Creation Time : Mon Oct 4 14:48:20 2004
Raid Level : raid5
Raid Devices : 4
Total Devices : 3
Preferred Minor : 1
Update Time : Sun Nov 20 01:11:15 2005
State : clean
Active Devices : 2
Working Devices : 3
Failed Devices : 2
Spare Devices : 1
Checksum : dfd92d15 - correct
Events : 0.5800013
Layout : left-symmetric
Chunk Size : 32K
Number Major Minor RaidDevice State
this 4 34 1 4 spare /dev/hdg1
0 0 3 1 0 active sync /dev/hda1
1 1 0 0 1 faulty removed
2 2 33 1 2 active sync /dev/hde1
3 3 0 0 3 faulty removed
4 4 34 1 4 spare /dev/hdg1
/dev/hde1:
Magic : a92b4efc
Version : 00.90.00
UUID : a38910a6:51582805:6ccb5711:4ac501b2
Creation Time : Mon Oct 4 14:48:20 2004
Raid Level : raid5
Raid Devices : 4
Total Devices : 3
Preferred Minor : 1
Update Time : Sun Nov 20 01:11:15 2005
State : clean
Active Devices : 2
Working Devices : 3
Failed Devices : 2
Spare Devices : 1
Checksum : dfd92d16 - correct
Events : 0.5800013
Layout : left-symmetric
Chunk Size : 32K
Number Major Minor RaidDevice State
this 2 33 1 2 active sync /dev/hde1
0 0 3 1 0 active sync /dev/hda1
1 1 0 0 1 faulty removed
2 2 33 1 2 active sync /dev/hde1
3 3 0 0 3 faulty removed
4 4 34 1 4 spare /dev/hdg1
/dev/hdc1:
Magic : a92b4efc
Version : 00.90.00
UUID : a38910a6:51582805:6ccb5711:4ac501b2
Creation Time : Mon Oct 4 14:48:20 2004
Raid Level : raid5
Raid Devices : 4
Total Devices : 4
Preferred Minor : 1
Update Time : Sun Nov 20 01:10:31 2005
State : clean
Active Devices : 2
Working Devices : 4
Failed Devices : 2
Spare Devices : 2
Checksum : dfd92d01 - correct
Events : 0.5800012
Layout : left-symmetric
Chunk Size : 32K
Number Major Minor RaidDevice State
this 5 22 1 5 spare /dev/hdc1
0 0 3 1 0 active sync /dev/hda1
1 1 0 0 1 faulty removed
2 2 33 1 2 active sync /dev/hde1
3 3 0 0 3 faulty removed
4 4 34 1 4 spare /dev/hdg1
5 5 22 1 5 spare /dev/hdc1
/dev/hda1:
Magic : a92b4efc
Version : 00.90.00
UUID : a38910a6:51582805:6ccb5711:4ac501b2
Creation Time : Mon Oct 4 14:48:20 2004
Raid Level : raid5
Raid Devices : 4
Total Devices : 3
Preferred Minor : 1
Update Time : Sun Nov 20 01:11:15 2005
State : clean
Active Devices : 2
Working Devices : 3
Failed Devices : 2
Spare Devices : 1
Checksum : dfd92cf4 - correct
Events : 0.5800013
Layout : left-symmetric
Chunk Size : 32K
Number Major Minor RaidDevice State
this 0 3 1 0 active sync /dev/hda1
0 0 3 1 0 active sync /dev/hda1
1 1 0 0 1 faulty removed
2 2 33 1 2 active sync /dev/hde1
3 3 0 0 3 faulty removed
4 4 34 1 4 spare /dev/hdg1
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