While switching the disks a RAID 1 is based on I used the --wait command
to wait for the rebuild to finish. It returned immediately, but a
subsequent query showed it had not been rebuilt. Have I misunderstood
something, or is this an error?
While doing these commands a much larger rebuild was going on with a
different array, involving some of the same physical disks but different
partitions. The partitions being rebuilt are on different physical
disks for the different arrays.
Here are the logs, with version info at the end (Debian Lenny + more
recent kernel):
markov:~# date; mdadm --detail /dev/md0
Tue Nov 20 09:37:07 PST 2012
/dev/md0:
Version : 00.90
Creation Time : Mon Dec 15 06:49:51 2008
Raid Level : raid1
Array Size : 96256 (94.02 MiB 98.57 MB)
Used Dev Size : 96256 (94.02 MiB 98.57 MB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Tue Nov 20 07:41:04 2012
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
UUID : 313d5489:7869305b:5b5da825:51e3856c
Events : 0.1602
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 33 1 active sync /dev/sdc1
markov:~# date; mdadm --fail /dev/md0 /dev/sdc1
Tue Nov 20 09:37:58 PST 2012
mdadm: set /dev/sdc1 faulty in /dev/md0
markov:~# date; mdadm --add /dev/md0 /dev/sdd2
Tue Nov 20 09:39:05 PST 2012
mdadm: added /dev/sdd2
markov:~# date; mdadm --detail /dev/md0
Tue Nov 20 09:39:14 PST 2012
/dev/md0:
Version : 00.90
Creation Time : Mon Dec 15 06:49:51 2008
Raid Level : raid1
Array Size : 96256 (94.02 MiB 98.57 MB)
Used Dev Size : 96256 (94.02 MiB 98.57 MB)
Raid Devices : 2
Total Devices : 3
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Tue Nov 20 09:39:05 2012
State : clean, degraded
Active Devices : 1
Working Devices : 2
Failed Devices : 1
Spare Devices : 1
UUID : 313d5489:7869305b:5b5da825:51e3856c
Events : 0.1606
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
2 8 50 1 spare rebuilding /dev/sdd2
3 8 33 - faulty spare /dev/sdc1
markov:~# time mdadm --wait /dev/md0; date
real 0m0.002s
user 0m0.000s
sys 0m0.004s
Tue Nov 20 09:40:07 PST 2012
markov:~# date; mdadm --detail /dev/md0
Tue Nov 20 09:40:20 PST 2012
/dev/md0:
Version : 00.90
Creation Time : Mon Dec 15 06:49:51 2008
Raid Level : raid1
Array Size : 96256 (94.02 MiB 98.57 MB)
Used Dev Size : 96256 (94.02 MiB 98.57 MB)
Raid Devices : 2
Total Devices : 3
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Tue Nov 20 09:39:15 2012
State : clean, degraded
Active Devices : 1
Working Devices : 2
Failed Devices : 1
Spare Devices : 1
UUID : 313d5489:7869305b:5b5da825:51e3856c
Events : 0.1608
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
2 8 50 1 spare rebuilding /dev/sdd2
3 8 33 - faulty spare /dev/sdc1
markov:~# uname -a
Linux markov 2.6.32-5-amd64 #1 SMP Wed Jan 12 03:40:32 UTC 2011 x86_64 GNU/Linux
markov:~# mdadm --version
mdadm - v2.6.7.2 - 14th November 2008
I notice that in this case, unlike the other array, the message during
the rebuild (the last detail report) does not include a line like
Rebuild Status : 0% complete
I just tried --wait again to see if there was some kind of race, but
once again it returned immediately, though detail says the spare is
rebuilding.
Ross Boylan
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