Estou executando o Fedora 19 (kernel 3.11.3-201.fc19.x86_64) com uma configuração de software RAID-1 (mdadm) em duas unidades Seagate de 1 GB idênticas:
# cat /proc/mdstat
Personalities : [raid1]
md1 : active raid1 sdb3[1] sda3[0]
973827010 blocks super 1.2 [2/2] [UU]
unused devices: <none>
Recentemente, alguns erros estão sendo apresentados em uma das duas unidades: o smartd detectou "1 setores atualmente ilegíveis (pendentes)" e "1 setores incorrigíveis offline". A matriz RAID "reescalonou" alguns setores. Então, cerca de um dia depois, o kernel produziu várias mensagens / exceções de E / S:
Oct 18 06:39:20 x smartd[461]: Device: /dev/sdb [SAT], 1 Currently unreadable (pending) sectors
Oct 18 06:39:20 x smartd[461]: Device: /dev/sdb [SAT], 1 Offline uncorrectable sectors
...
Oct 18 07:09:20 x smartd[461]: Device: /dev/sdb [SAT], 1 Currently unreadable (pending) sectors
Oct 18 07:09:20 x smartd[461]: Device: /dev/sdb [SAT], 1 Offline uncorrectable sectors
...
Oct 18 07:30:28 x kernel: [467502.192792] md/raid1:md1: sdb3: rescheduling sector 1849689328
Oct 18 07:30:28 x kernel: [467502.192822] md/raid1:md1: sdb3: rescheduling sector 1849689336
Oct 18 07:30:28 x kernel: [467502.192846] md/raid1:md1: sdb3: rescheduling sector 1849689344
Oct 18 07:30:28 x kernel: [467502.192870] md/raid1:md1: sdb3: rescheduling sector 1849689352
Oct 18 07:30:28 x kernel: [467502.192895] md/raid1:md1: sdb3: rescheduling sector 1849689360
Oct 18 07:30:28 x kernel: [467502.192919] md/raid1:md1: sdb3: rescheduling sector 1849689368
Oct 18 07:30:28 x kernel: [467502.192943] md/raid1:md1: sdb3: rescheduling sector 1849689376
Oct 18 07:30:28 x kernel: [467502.192966] md/raid1:md1: sdb3: rescheduling sector 1849689384
Oct 18 07:30:28 x kernel: [467502.192991] md/raid1:md1: sdb3: rescheduling sector 1849689392
Oct 18 07:30:28 x kernel: [467502.193035] md/raid1:md1: sdb3: rescheduling sector 1849689400
...
Oct 19 06:26:08 x kernel: [550035.944191] ata3.01: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Oct 19 06:26:08 x kernel: [550035.944224] ata3.01: BMDMA stat 0x64
Oct 19 06:26:08 x kernel: [550035.944248] ata3.01: failed command: READ DMA EXT
Oct 19 06:26:08 x kernel: [550035.944274] ata3.01: cmd 25/00:08:15:fb:9c/00:00:6c:00:00/f0 tag 0 dma 4096 in
Oct 19 06:26:08 x kernel: [550035.944274] res 51/40:00:1c:fb:9c/40:00:6c:00:00/10 Emask 0x9 (media error)
Oct 19 06:26:08 x kernel: [550035.944322] ata3.01: status: { DRDY ERR }
Oct 19 06:26:08 x kernel: [550035.944340] ata3.01: error: { UNC }
Oct 19 06:26:08 x kernel: [550036.573438] ata3.00: configured for UDMA/133
Oct 19 06:26:08 x kernel: [550036.621444] ata3.01: configured for UDMA/133
Oct 19 06:26:08 x kernel: [550036.621507] sd 2:0:1:0: [sdb] Unhandled sense code
Oct 19 06:26:08 x kernel: [550036.621516] sd 2:0:1:0: [sdb]
Oct 19 06:26:08 x kernel: [550036.621523] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Oct 19 06:26:08 x kernel: [550036.621530] sd 2:0:1:0: [sdb]
Oct 19 06:26:08 x kernel: [550036.621537] Sense Key : Medium Error [current] [descriptor]
Oct 19 06:26:08 x kernel: [550036.621555] Descriptor sense data with sense descriptors (in hex):
Oct 19 06:26:08 x kernel: [550036.621562] 72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
Oct 19 06:26:08 x kernel: [550036.621606] 6c 9c fb 1c
Oct 19 06:26:08 x kernel: [550036.621626] sd 2:0:1:0: [sdb]
Oct 19 06:26:08 x kernel: [550036.621638] Add. Sense: Unrecovered read error - auto reallocate failed
Oct 19 06:26:08 x kernel: [550036.621646] sd 2:0:1:0: [sdb] CDB:
Oct 19 06:26:08 x kernel: [550036.621653] Read(10): 28 00 6c 9c fb 15 00 00 08 00
Oct 19 06:26:08 x kernel: [550036.621692] end_request: I/O error, dev sdb, sector 1822227228
Oct 19 06:26:08 x kernel: [550036.621719] raid1_end_read_request: 9 callbacks suppressed
Oct 19 06:26:08 x kernel: [550036.621727] md/raid1:md1: sdb3: rescheduling sector 1816361448
Oct 19 06:26:08 x kernel: [550036.621782] ata3: EH complete
Oct 19 06:26:08 x kernel: [550041.155637] ata3.01: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Oct 19 06:26:08 x kernel: [550041.155669] ata3.01: BMDMA stat 0x64
Oct 19 06:26:08 x kernel: [550041.155694] ata3.01: failed command: READ DMA EXT
Oct 19 06:26:08 x kernel: [550041.155719] ata3.01: cmd 25/00:08:15:fb:9c/00:00:6c:00:00/f0 tag 0 dma 4096 in
Oct 19 06:26:08 x kernel: [550041.155719] res 51/40:00:1c:fb:9c/40:00:6c:00:00/10 Emask 0x9 (media error)
Oct 19 06:26:08 x kernel: [550041.155767] ata3.01: status: { DRDY ERR }
Oct 19 06:26:08 x kernel: [550041.155785] ata3.01: error: { UNC }
Oct 19 06:26:08 x kernel: [550041.343437] ata3.00: configured for UDMA/133
Oct 19 06:26:08 x kernel: [550041.391438] ata3.01: configured for UDMA/133
Oct 19 06:26:08 x kernel: [550041.391501] sd 2:0:1:0: [sdb] Unhandled sense code
Oct 19 06:26:08 x kernel: [550041.391510] sd 2:0:1:0: [sdb]
Oct 19 06:26:08 x kernel: [550041.391517] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Oct 19 06:26:08 x kernel: [550041.391525] sd 2:0:1:0: [sdb]
Oct 19 06:26:08 x kernel: [550041.391532] Sense Key : Medium Error [current] [descriptor]
Oct 19 06:26:08 x kernel: [550041.391546] Descriptor sense data with sense descriptors (in hex):
Oct 19 06:26:08 x kernel: [550041.391553] 72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
Oct 19 06:26:08 x kernel: [550041.391596] 6c 9c fb 1c
Oct 19 06:26:08 x kernel: [550041.391616] sd 2:0:1:0: [sdb]
Oct 19 06:26:08 x kernel: [550041.391624] Add. Sense: Unrecovered read error - auto reallocate failed
Oct 19 06:26:08 x kernel: [550041.391636] sd 2:0:1:0: [sdb] CDB:
Oct 19 06:26:08 x kernel: [550041.391643] Read(10): 28 00 6c 9c fb 15 00 00 08 00
Oct 19 06:26:08 x kernel: [550041.391681] end_request: I/O error, dev sdb, sector 1822227228
Oct 19 06:26:08 x kernel: [550041.391737] ata3: EH complete
Oct 19 06:26:08 x kernel: [550041.409686] md/raid1:md1: read error corrected (8 sectors at 1816363496 on sdb3)
Oct 19 06:26:08 x kernel: [550041.409705] handle_read_error: 9 callbacks suppressed
Oct 19 06:26:08 x kernel: [550041.409709] md/raid1:md1: redirecting sector 1816361448 to other mirror: sda3
O computador continuou a registrar algumas entradas no syslog até cerca de uma hora depois, e finalmente ficou completamente sem resposta. Nenhum "kernel oops" foi gravado no syslog. O computador teve que ser reinicializado, ponto em que a matriz de ataque estava em um status de ressincronização. Após a ressincronização, tudo parece bem e as unidades parecem estar funcionando normalmente.
Eu também notei que todos os setores reprogramados são exatamente 8 setores à parte, o que parece muito estranho para mim.
Por fim, após a reinicialização e aproximadamente um ou dois dias depois, mas significativamente após a conclusão da ressincronização do RAID, a unidade redefiniu a contagem incorreta do setor ilegível (pendente) e offline, o que acredito ser normal, pois a unidade coloca esses setores offline e remapeia:
Oct 20 01:05:42 x kernel: [ 2.186400] md: bind<sda3>
Oct 20 01:05:42 x kernel: [ 2.204826] md: bind<sdb3>
Oct 20 01:05:42 x kernel: [ 2.209618] md: raid1 personality registered for level 1
Oct 20 01:05:42 x kernel: [ 2.210079] md/raid1:md1: not clean -- starting background reconstruction
Oct 20 01:05:42 x kernel: [ 2.210087] md/raid1:md1: active with 2 out of 2 mirrors
Oct 20 01:05:42 x kernel: [ 2.210122] md1: detected capacity change from 0 to 997198858240
Oct 20 01:05:42 x kernel: [ 2.210903] md: resync of RAID array md1
Oct 20 01:05:42 x kernel: [ 2.210911] md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
Oct 20 01:05:42 x kernel: [ 2.210915] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for resync.
Oct 20 01:05:42 x kernel: [ 2.210920] md: using 128k window, over a total of 973827010k.
Oct 20 01:05:42 x kernel: [ 2.241676] md1: unknown partition table
...
Oct 20 06:33:10 x kernel: [19672.235467] md: md1: resync done.
...
Oct 21 05:35:50 x smartd[455]: Device: /dev/sdb [SAT], No more Currently unreadable (pending) sectors, warning condition reset after 1 email
Oct 21 05:35:50 x smartd[455]: Device: /dev/sdb [SAT], No more Offline uncorrectable sectors, warning condition reset after 1 email
smartctl -a /dev/sdb
agora mostra
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
...
5 Reallocated_Sector_Ct 0x0033 096 096 036 Pre-fail Always - 195
...
197 Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0010 100 100 000 Old_age Offline - 0
...
Algumas questões surgem:
1) Por que todos os setores remarcados seriam exatamente 8 separados?
2) Por que o kernel não responde e requer uma reinicialização? Não deveria ser exatamente a situação em que o RAID-1 deveria funcionar sem que o sistema explodisse?
3) Por que as contagens ilegíveis e ilegíveis off-line são redefinidas apenas 23 horas após a conclusão da ressincronização da invasão?