mark spare as active sync device?

mark spare as active sync device?

[Lars Täuber]

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?

Is there any chance to get data from this array?

Thanks
Lars

Re: mark spare as active sync device?

[NeilBrown]

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 ??

> 
> 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

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.

NeilBrown

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Re: mark spare as active sync device?

[Lars Täuber]

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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