Re: RAID5: mkraid --force /dev/md0 doesn't work properly

From: Jakob Østergaard (jakob@unthought.net)
Date: Sun Sep 30 2001 - 19:41:30 EST


On Sun, Sep 30, 2001 at 07:29:06PM -0500, Evan Harris wrote:
>
> And yes, I'm using the real --force option. :)

Good (hush now, it's a secret ;)

>
> I have a 6 disk RAID5 scsi array that had one disk go offline through a
> dying power supply, taking the array into degraded mode, and then another
> went offline a couple of hours later from what I think was a loose cable.
>
> The first drive to go offline was /dev/sde1.
> The second to go offline was /dev/sdd1.
>
> Both drives are actually fine after fixing the connection problems and a
> reboot, but since the superblocks are out of sync, it won't init.

Ok.

...
[huge snip]
...
>
> I set the first disk that went offline out with a failed-disk directive, and
> tried to recover with a:
>
> mkraid --force /dev/md0

Good !

(to anyone reading this without having read the docs: don't pull this trick
 unless you absolutely positively understand the consequences of screwing up
 here)

>
> I'm _positive_ that the /etc/raidtab is correct, but it fails to force the
> update with:
>
> DESTROYING the contents of /dev/md0 in 5 seconds, Ctrl-C if unsure!
> handling MD device /dev/md0
> analyzing super-block
> raid_disk conflict on /dev/sde1 and /dev/sdi1 (1)
> mkraid: aborted, see the syslog and /proc/mdstat for potential clues.
...

Read on

[snip]
> For info, here is my raidtab:
>
> raiddev /dev/md0
> raid-level 5
> nr-raid-disks 6
> nr-spare-disks 0
> chunk-size 256
> persistent-superblock 1
> device /dev/sdd1
> raid-disk 0
> device /dev/sde1
> raid-disk 1
> device /dev/sdf1
> raid-disk 2
> device /dev/sdg1
> raid-disk 3
> device /dev/sdh1
> raid-disk 4
> device /dev/sdi1
> raid-disk 5
> failed-disk 1

Wrong ! device /dev/sdi1 is railed-disk 5 not failed-disk 1,
that's why mkraid is confused.

What you want is:
      device /dev/sdd1
      raid-disk 0
      device /dev/sde1
      raid-disk 1
      device /dev/sdf1
      raid-disk 2
      device /dev/sdg1
      raid-disk 3
      device /dev/sdh1
      raid-disk 4
      device /dev/sdi1
      failed-disk 5

Good luck,

-- 
................................................................
:   jakob@unthought.net   : And I see the elder races,         :
:.........................: putrid forms of man                :
:   Jakob Østergaard      : See him rise and claim the earth,  :
:        OZ9ABN           : his downfall is at hand.           :
:.........................:............{Konkhra}...............:
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Sun Sep 30 2001 - 21:01:15 EST