[aklug] Re: Need help repairing an Ubuntu raid 5 array

Clay,
Just for information
In general fsck should NEVER be run to fix disk errors in a Raid 5 array..because .RAID-5 arrays do not contain a file
system that fsck can read,so you
cannot use fsck to do preliminary checking and/or repair; you must
use ckraid
The ckraid command can be safely run without the --fix option
to verify the inactive RAID array without making any changes.
When you are comfortable with the proposed changes, supply
the --fix option.
If you wish, you can try designating one of the disks as a ''failed
disk''. Do this with the --suggest-failed-disk-mask flag.
Only one bit should be set in the flag: RAID-5 cannot recover two
failed disks.
The mask is a binary bit mask: thus:
    0x1 == first disk
    0x2 == second disk
    0x4 == third disk
    0x8 == fourth disk, etc.
Some other tidbits learned at big blues disk recovery school are ---
If two drives in an array have bad sectors, then the array will not function properly even after a repair,
In fact it is very seldom the array will actually rebuild if it does however it will soon error out and you will be back where you started,
The recommended procedure on dual disks in a raid 5 array having sector errors is Replacement of both drives and recovering your data from back up to the devices
You might also consider defining an additional drive as a hot spare in the array, doing this will in the future allow failover of a disk to the hot spare sparing you the problems you now have.
hope this helps a bit

Pete

________________________________
From: CLAY SCOTT <rudeboy@gci.net>
To: aklug@aklug.org
Sent: Sat, December 26, 2009 11:52:24 PM
Subject: [aklug] Re: Need help repairing an Ubuntu raid 5 array

The boot process drops into a maintenance shell, but I can't fsck the drives. the array consists of sdb1 through sdf1 and fsck at first reported they were busy, then in the maintenance shell said they were available, but saw them as raid drives and complained that it couldn't find e2fsck.mdraid.

now in the livecd the disk monitoring application (which I clearly overlooked installing before) is showing bad sectors on sdc and sde. i'm running tests on them now.

If they can't be repaired I guess I'm looking at having to source some 500GB drives to get the array repaired so I can back it up. Pretty coincidental really considering I was looking to upgrade the array in a few weeks.

I'll let you know how the tests turn out.

~Clay

----- Original Message -----
From: Jim MacDonald <jim@macdonald.org>
Date: Saturday, December 26, 2009 9:22 pm
Subject: [aklug] Re: Need help repairing an Ubuntu raid 5 array
To: CLAY SCOTT <rudeboy@gci.net>
Cc: aklug@aklug.org

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Have you tried booting from a LiveCD to see if you can FSCK /dev/md0?
>
>
> CLAY SCOTT wrote:
> > My Ubutnu fileserver recently suffered a power failure and I
> haven't been able to get the raid5 array working since. I have been
> meaning to get it on a basic smart UPS that will shut it down
> during a blackout, but it looks like i dragged my feet too long.
> >
> > The boot process drops to the maintenance shell when it can't
> mount /dev/md0, but i'm not able to reassemble the array, check it,
> activate it or anything. I'm getting more and more out of practice
> as my life transitions more toward work and family life.
> >
> > I normally have hockey on Friday nights, but I was hoping there
> was a raid guru out there who could help me get it working again if
> I were to bring my fileserver down to FNL.
> >
> > I'm sure it's something stupid and simple I'm overlooking, but
> it's driving me nuts. Let me know if anyone is interested in
> lending a hand.
> >
> > ~Clay
> > ---------
> > To unsubscribe, send email to <aklug-request@aklug.org>
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Received on Mon Dec 28 01:19:58 2009