[Lustre-discuss] recovery from multiple disks failure on the same md
Kevin Van Maren
KVanMaren at fusionio.com
Mon May 7 08:38:43 PDT 2012
On May 6, 2012, at 10:13 PM, Tae Young Hong wrote:
Hi,
I found the terrible situation on our lustre system.
A OST (raid 6: 8+2, spare 1) had 2 disk failures almost at the same time. While recovering it, another disk failed. so recovering procedure seems to be halt, and the spare disk which were in resync fell into "spare" status again. (I guess that resync procedure almost finished more than 95%)
Right now we have just 7 disks for this md. Is there any possibility to recover from this situation?
It might be possible, but not something I've done. If the array has not been written to since a drive failed, you might be able to power-cycle the failed drives (to reset the firmware) and force re-add them (without a rebuild)? If the array _has_ been modified (most likely) you could write a sector of 0's to the bad sector, which will corrupt just that stripe, and force-re-add the last failed drive and attempt to rebuild again.
Certainly if you have a support contract I'd recommend you get professional assistance.
Unfortunately, the failure mode you encountered is all too common. Because the Linux SW RAID code does not read the parity blocks unless there is a problem, hard drive failures are NOT independent: drives appear to fail more often during a rebuild than at any other time. The only way to work around this problem is to periodically do a "verify" of the MD array.
A verify allows the drive, which is failing in the 20% of the space that contains parity, to fail _before_ the data becomes unreadable, rather than fail _after_ the data becomes unreadable. Don't do it on a degraded array, but it is a good way to ensure healthy arrays are really healthy.
"echo check > /sys/block/mdX/md/sync_action" to force a verify. Parity mis-matches will be reported (not corrected), but drive failures can be dealt with sooner, rather than letting them stack up. Do "man md" and see the "sync_action" section.
Also note that Lustre 1.8.7 has a fix to the SW RAID code (corruption when rebuilding under load). Oracle's release called the patch md-avoid-corrupted-ldiskfs-after-rebuild.patch, while Whamcloud called it raid5-rebuild-corrupt-bug.patch
Kevin
The following is detailed log.
#1 the original configuration before any failure
Number Major Minor RaidDevice State
0 8 176 0 active sync /dev/sdl
1 8 192 1 active sync /dev/sdm
2 8 208 2 active sync /dev/sdn
3 8 224 3 active sync /dev/sdo
4 8 240 4 active sync /dev/sdp
5 65 0 5 active sync /dev/sdq
6 65 16 6 active sync /dev/sdr
7 65 32 7 active sync /dev/sds
8 65 48 8 active sync /dev/sdt
9 65 96 9 active sync /dev/sdw
10 65 64 - spare /dev/sdu
#2 a disk(sdl) failed, and resync started after adding spare disk(sdu)
May 7 04:53:33 oss07 kernel: sd 1:0:10:0: SCSI error: return code = 0x08000002
May 7 04:53:33 oss07 kernel: sdl: Current: sense key: Medium Error
May 7 04:53:33 oss07 kernel: Add. Sense: Unrecovered read error
May 7 04:53:33 oss07 kernel:
May 7 04:53:33 oss07 kernel: Info fld=0x74241ace
May 7 04:53:33 oss07 kernel: end_request: I/O error, dev sdl, sector 1948523214
... ...
May 7 04:54:15 oss07 kernel: RAID5 conf printout:
May 7 04:54:16 oss07 kernel: --- rd:10 wd:9 fd:1
May 7 04:54:16 oss07 kernel: disk 1, o:1, dev:sdm
May 7 04:54:16 oss07 kernel: disk 2, o:1, dev:sdn
May 7 04:54:16 oss07 kernel: disk 3, o:1, dev:sdo
May 7 04:54:16 oss07 kernel: disk 4, o:1, dev:sdp
May 7 04:54:16 oss07 kernel: disk 5, o:1, dev:sdq
May 7 04:54:16 oss07 kernel: disk 6, o:1, dev:sdr
May 7 04:54:16 oss07 kernel: disk 7, o:1, dev:sds
May 7 04:54:16 oss07 kernel: disk 8, o:1, dev:sdt
May 7 04:54:16 oss07 kernel: disk 9, o:1, dev:sdw
May 7 04:54:16 oss07 kernel: RAID5 conf printout:
May 7 04:54:16 oss07 kernel: --- rd:10 wd:9 fd:1
May 7 04:54:16 oss07 kernel: disk 0, o:1, dev:sdu
May 7 04:54:16 oss07 kernel: disk 1, o:1, dev:sdm
May 7 04:54:16 oss07 kernel: disk 2, o:1, dev:sdn
May 7 04:54:16 oss07 kernel: disk 3, o:1, dev:sdo
May 7 04:54:16 oss07 kernel: disk 4, o:1, dev:sdp
May 7 04:54:16 oss07 kernel: disk 5, o:1, dev:sdq
May 7 04:54:16 oss07 kernel: disk 6, o:1, dev:sdr
May 7 04:54:16 oss07 kernel: disk 7, o:1, dev:sds
May 7 04:54:16 oss07 kernel: disk 8, o:1, dev:sdt
May 7 04:54:16 oss07 kernel: disk 9, o:1, dev:sdw
May 7 04:54:16 oss07 kernel: md: syncing RAID array md12
#3 another disk(sdp) failed
May 7 04:54:42 oss07 kernel: end_request: I/O error, dev sdp, sector 1949298688
May 7 04:54:42 oss07 kernel: mptbase: ioc1: LogInfo(0x31080000): Originator={PL}, Code={SATA NCQ FaCommands After Error}, SubCode(0x0000)
May 7 04:54:42 oss07 last message repeated 3 times
May 7 04:54:42 oss07 kernel: raid5:md12: read error not correctable (sector 1949298688 on sdp).
May 7 04:54:42 oss07 kernel: raid5: Disk failure on sdp, disabling device. Operation continuing on
May 7 04:54:43 oss07 kernel: end_request: I/O error, dev sdp, sector 1948532499
... ...
May 7 04:54:44 oss07 kernel: raid5:md12: read error not correctable (sector 1948532728 on sdp).
May 7 04:54:44 oss07 kernel: md: md12: sync done.
May 7 04:54:53 oss07 kernel: RAID5 conf printout:
May 7 04:54:53 oss07 kernel: --- rd:10 wd:8 fd:2
May 7 04:54:53 oss07 kernel: disk 0, o:1, dev:sdu
May 7 04:54:53 oss07 kernel: disk 1, o:1, dev:sdm
May 7 04:54:53 oss07 kernel: disk 2, o:1, dev:sdn
May 7 04:54:53 oss07 kernel: disk 3, o:1, dev:sdo
May 7 04:54:53 oss07 kernel: disk 4, o:0, dev:sdp
May 7 04:54:53 oss07 kernel: disk 5, o:1, dev:sdq
May 7 04:54:53 oss07 kernel: disk 6, o:1, dev:sdr
May 7 04:54:53 oss07 kernel: disk 7, o:1, dev:sds
May 7 04:54:53 oss07 kernel: disk 8, o:1, dev:sdt
May 7 04:54:53 oss07 kernel: disk 9, o:1, dev:sdw
... ...
May 7 04:54:54 oss07 kernel: RAID5 conf printout:
May 7 04:54:54 oss07 kernel: --- rd:10 wd:8 fd:2
May 7 04:54:54 oss07 kernel: disk 1, o:1, dev:sdm
May 7 04:54:54 oss07 kernel: disk 2, o:1, dev:sdn
May 7 04:54:54 oss07 kernel: disk 3, o:1, dev:sdo
May 7 04:54:54 oss07 kernel: disk 5, o:1, dev:sdq
May 7 04:54:54 oss07 kernel: disk 6, o:1, dev:sdr
May 7 04:54:54 oss07 kernel: disk 7, o:1, dev:sds
May 7 04:54:54 oss07 kernel: disk 8, o:1, dev:sdt
May 7 04:54:54 oss07 kernel: disk 9, o:1, dev:sdw
May 7 04:54:54 oss07 kernel: RAID5 conf printout:
May 7 04:54:54 oss07 kernel: --- rd:10 wd:8 fd:2
May 7 04:54:54 oss07 kernel: disk 0, o:1, dev:sdu
May 7 04:54:54 oss07 kernel: disk 1, o:1, dev:sdm
May 7 04:54:54 oss07 kernel: disk 2, o:1, dev:sdn
May 7 04:54:54 oss07 kernel: disk 3, o:1, dev:sdo
May 7 04:54:54 oss07 kernel: disk 5, o:1, dev:sdq
May 7 04:54:54 oss07 kernel: disk 6, o:1, dev:sdr
May 7 04:54:54 oss07 kernel: disk 7, o:1, dev:sds
May 7 04:54:55 oss07 kernel: disk 8, o:1, dev:sdt
May 7 04:54:55 oss07 kernel: disk 9, o:1, dev:sdw
May 7 04:54:55 oss07 kernel: md: syncing RAID array md12
# the 3rd disk(sdm) failed while resyncing
May 7 09:41:53 oss07 kernel: mptbase: ioc1: LogInfo(0x31080000): Originator={PL}, Code={SATA NCQ Fail All Commands After Error}, SubCode(0x0000)
May 7 09:41:57 oss07 kernel: mptbase: ioc1: LogInfo(0x31110e00): Originator={PL}, Code={Reset}, SubCode(0x0e00)
May 7 09:41:59 oss07 last message repeated 24 times
May 7 09:42:04 oss07 kernel: mptbase: ioc1: LogInfo(0x31080000): Originator={PL}, Code={SATA NCQ Fail All Commands After Error}, SubCode(0x0000)
May 7 09:42:34 oss07 last message repeated 43 times
May 7 09:42:34 oss07 kernel: sd 1:0:11:0: SCSI error: return code = 0x000b0000
May 7 09:42:34 oss07 kernel: end_request: I/O error, dev sdm, sector 1948444160
May 7 09:42:34 oss07 kernel: mptbase: ioc1: LogInfo(0x31080000): Originator={PL}, Code={SATA NCQ Fail All Commands After Error}, SubCode(0x0000)
May 7 09:42:34 oss07 last message repeated 3 times
May 7 09:42:34 oss07 kernel: raid5:md12: read error not correctable (sector 1948444160 on sdm).
May 7 09:42:34 oss07 kernel: raid5: Disk failure on sdm, disabling device. Operation continuing on 7 devices
May 7 09:42:34 oss07 kernel: raid5:md12: read error not correctable (sector 1948444168 on sdm).
May 7 09:42:34 oss07 kernel: raid5:md12: read error not correctable (sector 1948444176 on sdm).
... ...
May 7 09:42:49 oss07 kernel: --- rd:10 wd:7 fd:3
May 7 09:42:49 oss07 kernel: disk 0, o:1, dev:sdu
May 7 09:42:49 oss07 kernel: disk 1, o:0, dev:sdm
May 7 09:42:49 oss07 kernel: disk 2, o:1, dev:sdn
May 7 09:42:49 oss07 kernel: disk 3, o:1, dev:sdo
May 7 09:42:49 oss07 kernel: disk 5, o:1, dev:sdq
May 7 09:42:49 oss07 kernel: disk 6, o:1, dev:sdr
May 7 09:42:49 oss07 kernel: disk 7, o:1, dev:sds
May 7 09:42:49 oss07 kernel: disk 8, o:1, dev:sdt
May 7 09:42:49 oss07 kernel: disk 9, o:1, dev:sdw
... ...
May 7 09:42:58 oss07 kernel: RAID5 conf printout:
May 7 09:42:58 oss07 kernel: --- rd:10 wd:7 fd:3
May 7 09:42:58 oss07 kernel: disk 1, o:0, dev:sdm
May 7 09:42:58 oss07 kernel: disk 2, o:1, dev:sdn
May 7 09:42:58 oss07 kernel: disk 3, o:1, dev:sdo
May 7 09:42:58 oss07 kernel: disk 5, o:1, dev:sdq
May 7 09:42:58 oss07 kernel: disk 6, o:1, dev:sdr
May 7 09:42:58 oss07 kernel: disk 7, o:1, dev:sds
May 7 09:42:58 oss07 kernel: disk 8, o:1, dev:sdt
May 7 09:42:58 oss07 kernel: disk 9, o:1, dev:sdw
# current md status
[root at oss07 ~]# mdadm --detail /dev/md12
/dev/md12:
Version : 00.90.03
Creation Time : Mon Oct 4 15:30:53 2010
Raid Level : raid6
Array Size : 7814099968 (7452.11 GiB 8001.64 GB)
Used Dev Size : 976762496 (931.51 GiB 1000.20 GB)
Raid Devices : 10
Total Devices : 11
Preferred Minor : 12
Persistence : Superblock is persistent
Intent Bitmap : /mnt/scratch/bitmaps/ost02/bitmap
Update Time : Mon May 7 11:38:51 2012
State : clean, degraded
Active Devices : 7
Working Devices : 8
Failed Devices : 3
Spare Devices : 1
Chunk Size : 128K
UUID : 63eb5b15:294c1354:f0c167bd:f8e81f47
Events : 0.7382
Number Major Minor RaidDevice State
0 0 0 0 removed
1 0 0 1 removed
2 8 208 2 active sync /dev/sdn
3 8 224 3 active sync /dev/sdo
4 0 0 4 removed
5 65 0 5 active sync /dev/sdq
6 65 16 6 active sync /dev/sdr
7 65 32 7 active sync /dev/sds
8 65 48 8 active sync /dev/sdt
9 65 96 9 active sync /dev/sdw
10 8 176 - faulty spare /dev/sdl
11 65 64 - spare /dev/sdu
12 8 240 - faulty spare /dev/sdp
13 8 192 - faulty spare /dev/sdm
Best regards,
Taeyoung Hong
Senior Researcher
Supercomputing Center of KISTI
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