Re: mark spare as active sync device?

["Lars Täuber" <taeuber@bbaw.de>]

Hello NeilBrown,

thank you really very much. You saved my day.

Am Thu, 16 Jun 2011 10:54:23 +1000
NeilBrown <neilb@suse.de> schrieb:

> On Wed, 15 Jun 2011 12:10:26 +0200 Lars Täuber <taeuber@bbaw.de> wrote:
> 
> > Hi there,
> > 
> > is it possible to mark a nearly completly synced device as active in sync?
> > 
> > There was failing a device shortly before a spare drive was completely
> > synced. I want to get the directory structure from the device.
> > 
> > md3 : active raid6 sdz[16] sdaf[13] sds[0] sdac[10] sdah[15] sdag[14] sdae
> > [12] sdad [11](F) sdab[9] sdaa[17](F) sdy[6] sdx[5] sdw[4] sdv[3] sdu[2]
> > sdt[1] 27349202944 blocks level 6, 64k chunk, algorithm 2 [16/13]
> > [UUUUUUU__UU_UUUU] [===================>.]  recovery = 98.3%
> > (1921986020/1953514496) finish=25.9min speed=20244K/sec
> > 
> > /dev/sdz was the device that was inserted and is now marked as spare. Is
> > it possible to mark sdz as active and in sync?
> 
> Not really.... and should you mark it as the in-sync member number 7, 8, or
> 11 ??

I can reconstruct the member number of sdz from the previous failure mails
from mdadm. What a nice feature!

> > 
> > Is there any chance to get data from this array?
> 
> Your best bet is to try to 'create' the array again using '--assume-clean'
> and putting the devices that you thing are working in the correct place.
> e.g. something like:
> 
>  mdadm -S /dev/md3
>  mdadm -C /dev/md3 --metadata=0.90 --level=6 --algorithm=2 --chunk=64 \
>    --raid-devices=16  --assume-clean \
>    /dev/sds /dev/sdt /dev/sdu /dev/sdv   \
>    /dev/sdw /dev/sdx /dev/sdy /dev/sdz   \
>    missing /dev/sdab /dev/sdac missing   \
>    /dev/sdae /dev/sdaf /dev/sdag /dev/sdah

This was the very right command line except for the algorithm option. This is
not available in my version.

> Then "fsck -n /dev/md3"  and see if it looks reasonably OK.
> If it doesn't, try placing /dev/sdz in place of a different 'missing'.
> 
> Of course you should double check the order of devices that I have given
> here, and all the other details.

Of course!

> NeilBrown

Thanks again for your help and your great tool!
Lars
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