RAID5 rebuild difficulties

RAID5 rebuild difficulties

[Eric BENARD / Free]

Hi,

I'm having some troubles to rebuild a software RAID5 after several power 
failures.
Does anyone have an idea on how I could resync superblock of 4 partitions in 
order to rebuild the raid without loosing data ?

Many thanks and best regards
Eric

[root@serv root]# mdadm -Eb /dev/hde8
ARRAY /dev/md5 level=raid5 num-devices=3 
UUID=adecf616:84cf5266:30d2b689:ec3729e7
   devices=/dev/hde8
[root@serv root]# mdadm -Eb /dev/hdf6
ARRAY /dev/md5 level=raid5 num-devices=3 
UUID=adecf616:84cf5266:30d2b689:ec3729e7
   devices=/dev/hdf6
[root@serv root]# mdadm -Eb /dev/hdg8
ARRAY /dev/md5 level=raid5 num-devices=3 
UUID=adecf616:84cf5266:310000c4:ec3729e7
   devices=/dev/hdg8
[root@serv root]# mdadm -Eb /dev/hdh6
ARRAY /dev/md5 level=raid5 num-devices=3 
UUID=adecf616:84cf5266:30d2b689:003729e7
   devices=/dev/hdh6

[root@serv root]# mdadm -Af /dev/md5 /dev/hde8 /dev/hdf6 /dev/hdg8 /dev/hdh6
mdadm: superblock on /dev/hdg8 doesn't match others - assembly aborted

[root@serv root]# mdadm -V
mdadm - v1.3.0 - 29 Jul 2003

Re: RAID5 rebuild difficulties

[Neil Brown]

On Wednesday August 20, ebenard@free.fr wrote:
> Hi,
> 
> I'm having some troubles to rebuild a software RAID5 after several power 
> failures.
> Does anyone have an idea on how I could resync superblock of 4 partitions in 
> order to rebuild the raid without loosing data ?
> 
> Many thanks and best regards
> Eric
> 
> [root@serv root]# mdadm -Eb /dev/hde8
> ARRAY /dev/md5 level=raid5 num-devices=3 
> UUID=adecf616:84cf5266:30d2b689:ec3729e7
>    devices=/dev/hde8
> [root@serv root]# mdadm -Eb /dev/hdf6
> ARRAY /dev/md5 level=raid5 num-devices=3 
> UUID=adecf616:84cf5266:30d2b689:ec3729e7
>    devices=/dev/hdf6
> [root@serv root]# mdadm -Eb /dev/hdg8
> ARRAY /dev/md5 level=raid5 num-devices=3 
> UUID=adecf616:84cf5266:310000c4:ec3729e7
>    devices=/dev/hdg8
> [root@serv root]# mdadm -Eb /dev/hdh6
> ARRAY /dev/md5 level=raid5 num-devices=3 
> UUID=adecf616:84cf5266:30d2b689:003729e7
>    devices=/dev/hdh6
> 
> [root@serv root]# mdadm -Af /dev/md5 /dev/hde8 /dev/hdf6 /dev/hdg8 /dev/hdh6
> mdadm: superblock on /dev/hdg8 doesn't match others - assembly
> aborted

Try leaving out /dev/hdg8:

  madm -Af /dev/md5 /dev/hde8 /dev/hdf6 /dev/hdg8 /dev/hdh6

hdg8 seem to have a different UUID anyway - are you sure it is part of
the same array.

NeilBrown

> 
> [root@serv root]# mdadm -V
> mdadm - v1.3.0 - 29 Jul 2003
> 
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