Re: RAID6 recover problem

[Nagilum]

You may be able to temporary revive one of your dead disks by putting them in a fridge (properly wrapped and protected against condensation water!!, search the net on how to do that).

Then you can mark them as bad and linux will sync to a spare.

I hope that helps.

----- Message from [EMAIL PROTECTED] ---------
    Date: Fri, 12 Oct 2007 16:42:07 +0200
    From: Ralf Müller <[EMAIL PROTECTED]>
Reply-To: Ralf Müller <[EMAIL PROTECTED]>
 Subject: RAID6 recover problem
      To: linux-raid@vger.kernel.org

As for your sdc, I'd test it outside of the raid (dd if=/dev/sdc of=/dev/null) to see if this is a real defect or 'just' a checksum error. Then you might also try the fridge (if it's a real defect) or just ignore the error. I think there is a special "dd" version which will not abort on a read error. With that you could also clone that drive (except the failing sectors ofcourse).

I have a 10 disk raid6 with internal write intent bitmap here
(softraid, build and managed via mdadm). For whatever reason one of the
3 promise SATA 300 TX controllers went offline and took 4 of these 10
disks with it. After reboot the array was assembled with 8 out of 10
disks - sda2 and sdb2 missing. When I tried to re-add sda2 sdc - which
is one of the "active" disks - reported a read error on sector 54631.
Ok - seems I have a problem.

I stopped all activities at this point to ask here what I can do to
reassemble the array with a minimum loss of data.

Except the offline disks sda2 and sdb2 all other disks report 19 dirty
chunks (mdadm -X). The offline disks report 7 dirty chunks.

If one needs any further data - just ask.

Hoping for assistance
Ralf Müller



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