Neil Brown (neilb@xxxxxxx) wrote on 21 January 2008 12:13:
>On Sunday January 20, carlos@xxxxxxxxxxxxxx wrote:
>> I've got a raid5 array with 5 disks where 2 failed. The failures are
>> occasional and only on a few sectors so I tried to assemble it with 4
>> disks anyway:
>>
>> # mdadm -A -f -R /dev/md<number> /dev/disk1 /dev/disk2 /dev/disk3 /dev/disk4
>>
>> However mdadm complains that one of the disks has an out-of-date
>> superblock and kicks it out, and then it cannot run the array with
>> only 3 disks.
>>
>> Shouldn't it adjust the superblock and assemble-run it anyway? That's
>> what -f is for, no? This is with kernel 2.6.22.16 and mdadm 2.6.4.
>
>Please provide actual commands and actual output.
>Also add "--verbose" to the assemble command
>Also provide "--examine" for all devices.
>Also provide any kernel log messages.
The command is
mdadm -A --verbose -f -R /dev/md3 /dev/sda4 /dev/sdc4 /dev/sde4 /dev/sdd4
The failed areas are sdb4 (which I didn't include above) and sdd4. I
did a "dd if=/dev/sdb4 of=/dev/hda4 bs=512 conv=noerror" and it
complained about roughly 10 bad sectors. I did "dd if=/dev/sdd4
of=/dev/hdc4 bs=512 conv=noerror" and there were no errors, that's why
I used sdd4 above. I tried to substitute hdc4 for sdd4, and hda4 for
sdb4, to no avail.
I don't have kernel logs because the failed area has /home and /var.
The double fault occurred during the holidays, so I don't know which
happened first. Below are the output of the command above and of
--examine.
mdadm: looking for devices for /dev/md3
mdadm: /dev/sda4 is identified as a member of /dev/md3, slot 0.
mdadm: /dev/sdc4 is identified as a member of /dev/md3, slot 2.
mdadm: /dev/sde4 is identified as a member of /dev/md3, slot 4.
mdadm: /dev/sdd4 is identified as a member of /dev/md3, slot 5.
mdadm: no uptodate device for slot 1 of /dev/md3
mdadm: added /dev/sdc4 to /dev/md3 as 2
mdadm: no uptodate device for slot 3 of /dev/md3
mdadm: added /dev/sde4 to /dev/md3 as 4
mdadm: added /dev/sdd4 to /dev/md3 as 5
mdadm: added /dev/sda4 to /dev/md3 as 0
mdadm: failed to RUN_ARRAY /dev/md3: Input/output error
mdadm: Not enough devices to start the array.
On screen it shows "kicking out of date..." for sdd4.
/dev/sda4:
Magic : a92b4efc
Version : 00.90.00
UUID : 2f2f8327:375b4306:94521055:e3dc373b
Creation Time : Tue May 11 16:03:35 2004
Raid Level : raid5
Used Dev Size : 70454400 (67.19 GiB 72.15 GB)
Array Size : 281817600 (268.76 GiB 288.58 GB)
Raid Devices : 5
Total Devices : 4
Preferred Minor : 3
Update Time : Wed Jan 16 16:00:53 2008
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 2
Spare Devices : 0
Checksum : 16119868 - correct
Events : 0.14967284
Layout : left-symmetric
Chunk Size : 128K
Number Major Minor RaidDevice State
this 0 8 4 0 active sync /dev/sda4
0 0 8 4 0 active sync /dev/sda4
1 1 0 0 1 active sync <- note the difference compared to sdc4
2 2 8 36 2 active sync /dev/sdc4
3 3 0 0 3 faulty removed
4 4 8 68 4 active sync /dev/sde4
/dev/sdc4:
Magic : a92b4efc
Version : 00.90.00
UUID : 2f2f8327:375b4306:94521055:e3dc373b
Creation Time : Tue May 11 16:03:35 2004
Raid Level : raid5
Used Dev Size : 70454400 (67.19 GiB 72.15 GB)
Array Size : 281817600 (268.76 GiB 288.58 GB)
Raid Devices : 5
Total Devices : 4
Preferred Minor : 3
Update Time : Wed Jan 16 16:00:53 2008
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 2
Spare Devices : 0
Checksum : 1611988f - correct
Events : 0.14967284
Layout : left-symmetric
Chunk Size : 128K
Number Major Minor RaidDevice State
this 2 8 36 2 active sync /dev/sdc4
0 0 8 4 0 active sync /dev/sda4
1 1 0 0 1 faulty removed
2 2 8 36 2 active sync /dev/sdc4
3 3 0 0 3 faulty removed
4 4 8 68 4 active sync /dev/sde4
/dev/sdd4:
Magic : a92b4efc
Version : 00.90.00
UUID : 2f2f8327:375b4306:94521055:e3dc373b
Creation Time : Tue May 11 16:03:35 2004
Raid Level : raid5
Used Dev Size : 70454400 (67.19 GiB 72.15 GB)
Array Size : 281817600 (268.76 GiB 288.58 GB)
Raid Devices : 5
Total Devices : 5
Preferred Minor : 3
Update Time : Fri Jan 11 18:45:17 2008
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 2
Spare Devices : 1
Checksum : 160b27ce - correct
Events : 0.14967266
Layout : left-symmetric
Chunk Size : 128K
Number Major Minor RaidDevice State
this 5 8 52 5 spare /dev/sdd4
0 0 8 4 0 active sync /dev/sda4
1 1 0 0 1 faulty removed
2 2 8 36 2 active sync /dev/sdc4
3 3 0 0 3 faulty removed
4 4 8 68 4 active sync /dev/sde4
5 5 8 52 5 spare /dev/sdd4
/dev/sde4:
Magic : a92b4efc
Version : 00.90.00
UUID : 2f2f8327:375b4306:94521055:e3dc373b
Creation Time : Tue May 11 16:03:35 2004
Raid Level : raid5
Used Dev Size : 70454400 (67.19 GiB 72.15 GB)
Array Size : 281817600 (268.76 GiB 288.58 GB)
Raid Devices : 5
Total Devices : 4
Preferred Minor : 3
Update Time : Wed Jan 16 16:00:53 2008
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 2
Spare Devices : 0
Checksum : 161198b3 - correct
Events : 0.14967284
Layout : left-symmetric
Chunk Size : 128K
Number Major Minor RaidDevice State
this 4 8 68 4 active sync /dev/sde4
0 0 8 4 0 active sync /dev/sda4
1 1 0 0 1 faulty removed
2 2 8 36 2 active sync /dev/sdc4
3 3 0 0 3 faulty removed
4 4 8 68 4 active sync /dev/sde4
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