I have (had) a 4 disk RAID5 /dev/sd[abcd]1.
sda went bad (really, bad sectors) and is being replaced, hope
to get a replacement tomorrow.
While the array was degraded (but running) sdd failed (controller
trouble) and was marked as failed. The array went down (naturally).
I am rather sure that sdd is healthy - see examine below.
Right now /dev/sd[bcd] are seen as sd[abc] until I install the
missing disk.
I wish to bring the array up (degraded). Whatever I do mdadm
refuses to do so
mdadm --assemble --force /dev/sd{a,b,c}1
should it recognise the array as degraded but good and start it?
Q1) What is the correct command to bring these three up as
degraded?
Q2) When I get the fourth disk, how do I bring the array up
ensuring that the good disks (sd[bcd]) are marked as such
and the fresh one (sda) is reconstructed (rather than one
of the good ones).
In the past in cases where I trusted all four to be good (again,
controller trouble would fail multiple disks) I would just --build
on top of the array and a would not care which one is being
reconstructed.
I assume that the below data does not reflect modified superblocks
due to the attempted --force because the date reflects the failure
event.
# mdadm --examine /dev/sd*1
/dev/sda1:
Magic : a92b4efc
Version : 00.90.02
UUID : 54069710:f9f9ab5b:ae89479a:d7c1852e
Creation Time : Tue Sep 13 00:42:04 2005
Raid Level : raid5
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Nov 27 15:29:01 2005
State : clean
Active Devices : 2
Working Devices : 3
Failed Devices : 2
Spare Devices : 1
Checksum : 16d99bd5 - correct
Events : 0.492477
Layout : left-symmetric
Chunk Size : 256K
Number Major Minor RaidDevice State
this 1 8 17 1 active sync /dev/.static/dev/sdb1
0 0 0 0 0 removed
1 1 8 17 1 active sync /dev/.static/dev/sdb1
2 2 22 1 2 active sync /dev/.static/dev/hdc1
3 3 0 0 3 faulty removed
4 4 8 1 4 faulty /dev/.static/dev/sda1
/dev/sdb1:
Magic : a92b4efc
Version : 00.90.02
UUID : 54069710:f9f9ab5b:ae89479a:d7c1852e
Creation Time : Tue Sep 13 00:42:04 2005
Raid Level : raid5
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Nov 27 15:29:01 2005
State : clean
Active Devices : 2
Working Devices : 3
Failed Devices : 2
Spare Devices : 1
Checksum : 16d99bd5 - correct
Events : 0.492477
Layout : left-symmetric
Chunk Size : 256K
Number Major Minor RaidDevice State
this 2 22 1 2 active sync /dev/.static/dev/hdc1
0 0 0 0 0 removed
1 1 8 17 1 active sync /dev/.static/dev/sdb1
2 2 22 1 2 active sync /dev/.static/dev/hdc1
3 3 0 0 3 faulty removed
4 4 8 1 4 faulty /dev/.static/dev/sda1
/dev/sdc1:
Magic : a92b4efc
Version : 00.90.02
UUID : 54069710:f9f9ab5b:ae89479a:d7c1852e
Creation Time : Tue Sep 13 00:42:04 2005
Raid Level : raid5
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Nov 27 15:29:01 2005
State : clean
Active Devices : 2
Working Devices : 3
Failed Devices : 2
Spare Devices : 1
Checksum : 16d99c17 - correct
Events : 0.492477
Layout : left-symmetric
Chunk Size : 256K
Number Major Minor RaidDevice State
this 5 22 65 5 spare /dev/.static/dev/hdd1
0 0 0 0 0 removed
1 1 8 17 1 active sync /dev/.static/dev/sdb1
2 2 22 1 2 active sync /dev/.static/dev/hdc1
3 3 0 0 3 faulty removed
4 4 8 1 4 faulty /dev/.static/dev/sda1
--
Eyal Lebedinsky (eyal@xxxxxxxxxxxxxx) <http://samba.org/eyal/>
attach .zip as .dat
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