Re: md RAID5: Disk wrongly marked "spare", need to force re-add it

[Oliver Schinagl <oliver+list@schinagl.nl>]

On 15-04-13 12:26, Ben Bucksch wrote:
> Oliver Schinagl wrote, On 14.04.2013 19:30:
>> mdadm --assemble --run --force /dev/md0 /dev/sd[1-7].
>> Make sure to mdadm --stop /dev/md0 before trying to assemble it. 
> # mdadm --stop /dev/md0
> mdadm: stopped /dev/md0
> # mdadm --assemble --run --force /dev/md0 /dev/sd[jlmnopq]
> mdadm: failed to RUN_ARRAY /dev/md0: Input/output error
> mdadm: Not enough devices to start the array.
> # cat /proc/mdstat
> md0 : inactive sdj[0] sdq[7] sdn[6] sdp[5] sdo[4] sdm[3]
>       5860574976 blocks
> (Note that sdl is not even listed)
> # mdadm --re-add /dev/md0 /dev/sdl
> mdadm: re-added /dev/sdl
That can't work I don't think. You want to create a degraded raid5 
array, e.g. 7 disks. It tried (and failed) to create a 6 disk array. 
Re-adding sdl will make it won't to resync. How you can force that 
however I don't know. I hoped for you that the above command would 
actually do that.
> # cat /proc/mdstat
> md0 : inactive sdl[8](S) sdj[0] sdq[7] sdn[6] sdp[5] sdo[4] sdm[3]
>       6837337472 blocks
>
> Now, sdl is listed, but as spare. I need it to be treated not as 
> spare, but as good drive with correct data (well, almost, 2 events off 
> only). How do I do that?
>
>
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