Re: Help with recovering a RAID5 array

[NeilBrown <neilb@suse.de>]

[-- Attachment #1: Type: text/plain, Size: 2383 bytes --]

On Sat, 04 May 2013 13:13:27 +0200 Stefan Borggraefe <stefan@spybot.info>
wrote:

> Am Freitag, 3. Mai 2013, 10:38:52 schrieben Sie:
> > On Thu, May 2, 2013 at 2:24 PM, Stefan Borggraefe <stefan@spybot.info> 
> wrote:
> > > I am using a RAID5 software RAID on Ubuntu 12.04
> > > 
> > > It consits of 6 Hitachi drives with 4 TB and contains an ext 4 file
> > > system.
> > > 
> > > When I returned to this server this morning, the array was in the
> > > following
> > > state:
> > > 
> > > md126 : active raid5 sdc1[7](S) sdh1[4] sdd1[3](F) sde1[0] sdg1[6] sdf1[2]
> > > 
> > >       19535086080 blocks super 1.2 level 5, 512k chunk, algorithm 2 [6/4]
> > > 
> > > [U_U_UU]
> > > 
> > > sdc is the newly added hard disk, but now also sdd failed. :( It would be
> > > great if there was a way to have the this RAID5 working again. Perhaps
> > > sdc1
> > > can then be fully added to the array and after this drive sdd also
> > > exchanged.
> > I have had a few raid6 fail in a similar fashion: the 3rd drive
> > faliing during rebuild (Also 4 TB Hitachi by the way).
> > 
> > I tested if the drives were fine:
> > 
> >   parallel dd if={} of=/dev/null bs=1000k ::: /dev/sd?
> > 
> > And they were all fine. 
> 
> Same for me.
> 
> > With only a few failing sectors (if any) I figured that very little
> > would be lost by forcing the failing drive online. Remove the spare
> > drive, and force the remaining online:
> > 
> >   mdadm -A --scan --force
> 
> I removed the spare /dev/sdc1 from /dev/md126
> 
> with
> 
> mdadm /dev/md126 --remove /dev/sdc1
> 
> After mdadm -A --scan --force the array is now in this state
> 
> md126 : active raid5 sdh1[4] sdd1[3](F) sde1[0] sdg1[6] sdf1[2]
>       19535086080 blocks super 1.2 level 5, 512k chunk, algorithm 2 [6/4] 
> [U_U_UU]

Did you stop the array first?
  i.e.
    mdadm --stop /dev/md126
    mdadm -Asfvv

NeilBrown


>  
> > Next step is to do fsck.
> 
> I think this is not possible yet at this point. Don't I need to reassemble the 
> array using the --assume-clean option and with one missing drive first? Some 
> step is missing here.
> 
> Stefan
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 828 bytes --]