Re: mdadm: Invalid Argument ("cannot start dirty degraded array")

[Mark Thompson <mark@ruthless.ws>]

David Wuertele wrote:
> I have a gentoo system (kernel 2.6.8-gentoo-r3) with a 7 drive RAID5
> array.  Recently that array went down, and I was advised by the list
> to try mdadm.  I was unsuccessful, but perhaps someone here can advise
> me where I went wrong.
> 
> When I boot, I see the "Starting up RAID devices: ... * Trying
> md0... [ !!FAILED ]" and the system drops me to the shell.  I type:
> 
>   # cat /proc/mdstat
>   Personalities : [raid1] [raid5]
>   md0 : inactive hdm4[0] hde2[6] hdo2[5] hdh2[4] hdf2[3] hdg2[2]
>         1464789888 blocks
>   unused devices: <none>
> 
> OK, the array is missing partition hdp2.  dmesg says it has an invalid
> superblock:
> 
>   # dmesg | grep hdp
>       ide7: BM-DMA at 0xd808-0xd80f, BIOS settings: hdo:DMA, hdp:DMA
>   hdp: WDC WD2500JB-00GVA0, ATA DISK drive
>   hdp: max request size: 1024KiB
>   hdp: 488397168 sectors (250059 MB) w/8192KiB Cache, CHS=30401/255/63, UDMA (100)
>   md: invalid raid superblock magic on hdp2
>   md: hdp2 has invalid sb, not importing!
>   Adding 64220k swap on /dev/hdp1.  Priority:-2 extents:1
> 
> I didn't see any indication that there is anything wrong with the hdp
> drive.  Here is my /etc/mdadm.conf file:
> 
>   # cat /etc/mdadm.conf
>   DEVICE partitions
>   ARRAY /dev/md0 level=raid5 num-devices=7 UUID=d312c423:e2eeeff5:3401806f:ab10e3c
>      devices=/dev/ide/host2/bus0/target0/lun0/part2,/dev/ide/host2/bus0/target1/lun0/part2,/dev/ide/host2/bus1/target0/lun0/part2,/dev/ide/host2/bus1/target1/lun0/part2,/dev/ide/host6/bus0/target0/lun0/part4,/dev/ide/host6/bus1/target0/lun0/part2
> 
> Since /proc/mdstat reports that six of the seven drives are already
> assembled, I tried running as-is:
> 
>   # mdadm --run /dev/md0
>   mdadm: failed to run array /dev/md0: Invalid argument
>   # mdadm -v --run --force /dev/md0
>   mdadm: failed to run array /dev/md0: Invalid argument
> 
> Hmm... not very descriptive.  I looked at the end of dmesg again for
> more hints:
> 
>   # dmesg | tail -18
>   md: pers->run() failed ...
>   raid5: device hdm4 operational as raid disk 0
>   raid5: device hde2 operational as raid disk 6
>   raid5: device hdo2 operational as raid disk 5
>   raid5: device hdh2 operational as raid disk 4
>   raid5: device hdf2 operational as raid disk 3
>   raid5: device hdg2 operational as raid disk 2
>   raid5: cannot start dirty degraded array for md0
>   RAID5 conf printout:
>    --- rd:7 wd:6 fd:1
>    disk 0, o:1, dev:hdm4
>    disk 2, o:1, dev:hdg2
>    disk 3, o:1, dev:hdf2
>    disk 4, o:1, dev:hdh2
>    disk 5, o:1, dev:hdo2
>    disk 6, o:1, dev:hde2
>   raid5: failed to run raid set md0
>   md: pers->run() failed ...
> 
> Any suggestions?
> Thanks,
> Dave

Hey there,

I had the exact issue on the weekend this is how I fixed it:
mdadm -S /dev/md0
mdadm -Af /dev/md0 /dev/hdm4 /dev/hde2 /dev/hdo2 /dev/hdh2 /dev/hdf2 
/dev/hdg2

That -should- start the array without hdp2, once its started, add 
/dev/hdp2 to the array and it should be all good.

mdadm -a /dev/md0 /dev/hdp2

Cheers,
Mark