Hello,
I am wondering how to identify a failed md array.
Lets assume the following array
/dev/md0:
Version : 1.2
Creation Time : Mon May 26 19:10:59 2014
Raid Level : raid1
Array Size : 10176 (9.94 MiB 10.42 MB)
Used Dev Size : 10176 (9.94 MiB 10.42 MB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Mon May 26 19:10:59 2014
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Name : test:0 (local to host test)
UUID : cac8fd48:44219a96:5de7e757:4e21a3e2
Events : 17
Number Major Minor RaidDevice State
0 254 0 0 active sync /dev/dm-0
1 254 1 1 active sync /dev/dm-1
with
/sys/block/md0/md/array_state:clean
/sys/block/md0/md/dev-dm-0/state:in_sync
/sys/block/md0/md/dev-dm-1/state:in_sync
and
disk0: 0 20480 linear 7:0 0
disk1: 0 20480 linear 7:1 0
If dm-0 gets changed to "disk0: 0 20480 error" and we read from the
array (dd if=/dev/md0 count=1 iflag=direct of=/dev/null) the broken
disk gets detected by md:
[84688.483607] md/raid1:md0: dm-0: rescheduling sector 0
[84688.483654] md/raid1:md0: redirecting sector 0 to other mirror: dm-1
[84688.483670] md: super_written gets error=-5, uptodate=0
[84688.483672] md/raid1:md0: Disk failure on dm-0, disabling device.
md/raid1:md0: Operation continuing on 1 devices.
[84688.483676] md: super_written gets error=-5, uptodate=0
[84688.494174] RAID1 conf printout:
[84688.494178] --- wd:1 rd:2
[84688.494181] disk 0, wo:1, o:0, dev:dm-0
[84688.494182] disk 1, wo:0, o:1, dev:dm-1
[84688.494183] RAID1 conf printout:
[84688.494184] --- wd:1 rd:2
[84688.494184] disk 1, wo:0, o:1, dev:dm-1
/dev/md0:
Version : 1.2
Creation Time : Mon May 26 19:10:59 2014
Raid Level : raid1
Array Size : 10176 (9.94 MiB 10.42 MB)
Used Dev Size : 10176 (9.94 MiB 10.42 MB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Mon May 26 19:27:41 2014
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 1
Spare Devices : 0
Name : test:0 (local to host test)
UUID : cac8fd48:44219a96:5de7e757:4e21a3e2
Events : 20
Number Major Minor RaidDevice State
0 0 0 0 removed
1 254 1 1 active sync /dev/dm-1
0 254 0 - faulty /dev/dm-0
md0 : active raid1 dm-1[1] dm-0[0](F)
10176 blocks super 1.2 [2/1] [_U]
/sys/block/md0/md/array_state:clean
/sys/block/md0/md/dev-dm-0/state:faulty,write_error
/sys/block/md0/md/dev-dm-1/state:in_sync
/sys/block/md0/md/degraded:1
However if I also change dm-1 to "disk1: 0 20480 error" and read
again there is no visible state change:
/dev/md0:
Version : 1.2
Creation Time : Mon May 26 19:10:59 2014
Raid Level : raid1
Array Size : 10176 (9.94 MiB 10.42 MB)
Used Dev Size : 10176 (9.94 MiB 10.42 MB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Mon May 26 19:27:41 2014
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 1
Spare Devices : 0
Number Major Minor RaidDevice State
0 0 0 0 removed
1 254 1 1 active sync /dev/dm-1
0 254 0 - faulty /dev/dm-0
md0 : active raid1 dm-1[1] dm-0[0](F)
10176 blocks super 1.2 [2/1] [_U]
/sys/block/md0/md/array_state:clean
/sys/block/md0/md/dev-dm-0/state:faulty,write_error
/sys/block/md0/md/dev-dm-1/state:in_sync
/sys/block/md0/md/degraded:1
On write to the array we get
[85498.660247] md: super_written gets error=-5, uptodate=0
[85498.666464] quiet_error: 268 callbacks suppressed
[85498.666470] Buffer I/O error on device md0, logical block 2528
[85498.666476] Buffer I/O error on device md0, logical block 2528
[85498.666486] Buffer I/O error on device md0, logical block 2542
[85498.666490] Buffer I/O error on device md0, logical block 2542
[85498.666496] Buffer I/O error on device md0, logical block 0
[85498.666499] Buffer I/O error on device md0, logical block 0
[85498.666508] Buffer I/O error on device md0, logical block 1
[85498.666512] Buffer I/O error on device md0, logical block 1
[85498.666518] Buffer I/O error on device md0, logical block 2543
[85498.666524] Buffer I/O error on device md0, logical block 2543
[85498.866388] md: super_written gets error=-5, uptodate=0
and the only change is
/sys/block/md0/md/dev-dm-1/state:in_sync,write_error,want_replacement
How can I identify a failed array?
array_state reports "clean", the last raid member stays "in_sync" and
the value in degraded doesn't equal raid_disks.
Sebastian
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