[mythtv-users] Totally OT - but need help wit RAID5 array

James Pifer jep at obrien-pifer.com
Fri Nov 17 12:21:55 UTC 2006


On Fri, 2006-11-17 at 08:54 +0000, Robin Hill wrote:
> On Thu Nov 16, 2006 at 08:24:05PM -0500, James Pifer wrote:
> 
> > ok, dd_rhelp finished. I switched the drives so the good drive is now
> > hdb. It still won't let me bring up md0:
> > [root at storage ~]# mdadm --assemble /dev/md0 --force /dev/hdb /dev/hdc
> > mdadm: /dev/md0 assembled from 1 drive - not enough to start the array.
> > 
> That's odd - the query information all looks okay.  The UUID for the
> drives is the same so it should see them as being in the same array.
> 
> All I can think of now is to re-create the array using the
> --assume-clean flag (so use the same command as earlier, including the
> typo, but put a --assume-clean after the /dev/md0) .  This should
> rewrite the metadata without touching the actual data.  I've never used
> this myself and it does come with a warning in the manual page, but if
> it won't assemble the array then I can't see any other solution.
> 
> If you do get the array working again with two drives, run a fsck on it,
> then hot-add the third drive (mdmadm -a /dev/md0 /dev/hdd).
> 

Ok, so you're saying run this command (with create?):
mdadm --create --verbose /dev/md0 --assume-clean --level=5 --raid-devices=3 /dev/hdb /dev/hdc dev/hdd
OR
mdadm --assemble /dev/md0 --assume-clean --force /dev/hdb /dev/hdc dev/hdd

Then, assuming that works ok and BEFORE mounting, run:
fsck /dev/md0

If I get past that, then run:
mdmadm -a /dev/md0 /dev/hdd

Sound right? Do I need to do anything about "dev/hdd" or just ignore?

Thanks,
James



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