Re: RAID5 faild while in degraded mode, need help

On Mon, 9 Jul 2012 13:02:04 +0200 Dietrich Heise [off-list ref] wrote:

Hello,

thanks for the hint.

I do a backup with dd before that, I hope I can get back the data of the raid.

The following is in the syslog:

Jul  8 19:21:15 p3 kernel: Buffer I/O error on device dm-1, logical
block 365625856
Jul  8 19:21:15 p3 kernel: Buffer I/O error on device dm-1, logical
block 365625856
Jul  8 19:21:15 p3 kernel: lost page write due to I/O error on dm-1
Jul  8 19:21:15 p3 kernel: lost page write due to I/O error on dm-1
Jul  8 19:21:15 p3 kernel: JBD: I/O error detected when updating
journal superblock for dm-1.
Jul  8 19:21:15 p3 kernel: JBD: I/O error detected when updating
journal superblock for dm-1.
Jul  8 19:21:15 p3 kernel: RAID conf printout:
Jul  8 19:21:15 p3 kernel: RAID conf printout:
Jul  8 19:21:15 p3 kernel: --- level:5 rd:4 wd:2
Jul  8 19:21:15 p3 kernel: --- level:5 rd:4 wd:2
Jul  8 19:21:15 p3 kernel: disk 0, o:1, dev:sdf1
Jul  8 19:21:15 p3 kernel: disk 0, o:1, dev:sdf1
Jul  8 19:21:15 p3 kernel: disk 1, o:1, dev:sde1
Jul  8 19:21:15 p3 kernel: disk 1, o:1, dev:sde1
Jul  8 19:21:15 p3 kernel: disk 2, o:1, dev:sdc1
Jul  8 19:21:15 p3 kernel: disk 2, o:1, dev:sdc1
Jul  8 19:21:15 p3 kernel: disk 3, o:0, dev:sdd1
Jul  8 19:21:15 p3 kernel: disk 3, o:0, dev:sdd1
Jul  8 19:21:15 p3 kernel: RAID conf printout:
Jul  8 19:21:15 p3 kernel: RAID conf printout:
Jul  8 19:21:15 p3 kernel: --- level:5 rd:4 wd:2
Jul  8 19:21:15 p3 kernel: --- level:5 rd:4 wd:2
Jul  8 19:21:15 p3 kernel: disk 0, o:1, dev:sdf1
Jul  8 19:21:15 p3 kernel: disk 0, o:1, dev:sdf1
Jul  8 19:21:15 p3 kernel: disk 1, o:1, dev:sde1
Jul  8 19:21:15 p3 kernel: disk 1, o:1, dev:sde1
Jul  8 19:21:15 p3 kernel: disk 2, o:1, dev:sdc1
Jul  8 19:21:15 p3 kernel: disk 2, o:1, dev:sdc1
Jul  8 19:21:15 p3 kernel: md: recovery of RAID array md0
Jul  8 19:21:15 p3 kernel: md: recovery of RAID array md0
Jul  8 19:21:15 p3 kernel: md: minimum _guaranteed_  speed: 1000 KB/sec/disk.
Jul  8 19:21:15 p3 kernel: md: minimum _guaranteed_  speed: 1000 KB/sec/disk.
Jul  8 19:21:15 p3 kernel: md: using maximum available idle IO
bandwidth (but not more than 200000 KB/sec) for recovery.
Jul  8 19:21:15 p3 kernel: md: using maximum available idle IO
bandwidth (but not more than 200000 KB/sec) for recovery.
Jul  8 19:21:15 p3 kernel: md: using 128k window, over a total of 1465126400k.
Jul  8 19:21:15 p3 kernel: md: using 128k window, over a total of 1465126400k.
Jul  8 19:21:15 p3 kernel: md: resuming recovery of md0 from checkpoint.
Jul  8 19:21:15 p3 kernel: md: resuming recovery of md0 from checkpoint.

I think the right order is sdf1 sde1 sdc1 sdd1, I am right?

Yes, that looks right.

So I have to do:

mdadm -C /dev/md1 -l5 -n4 -e 1.2 -c 512 /dev/sdf1 /dev/sde1 missing /dev/sdd1

The question is: sould I also add --assume-clean

--assume-clean makes no difference to a degraded raid5 so it doesn't really
matter.
However I always suggest using --assume-clean when re-creating an array so
on principle I would say "yes - you should add --assume-clean".

NeilBrown

Thanks!
Dietrich