> > -----Original Message-----
> > From:
linux-raid-owner@vger.kernel.org [mailto:linux-raid-
> > owner@vger.kernel.org] On Behalf Of Pierre Vignéras
> > Sent: Sunday, May 16, 2010 10:41 AM
> > To:
linux-raid@vger.kernel.org
> > Subject: mdadm: failed devices become spares!
> >
> > Hi,
> >
> > I encountered a critical problem with mdadm that I submitted to the
> > Debian mailing list (it's a debian lenny/stable). They asked me to submit
> > this to you. So that's what I do.
> >
> > To prevent duplication of description/information, I give you the URL of
> > that
> > bug description:
> >
> >
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=578352
> >
> > If you prefer the full stuff to be copy/pasted to that mailing list, just
> > ask
> > for it.
> >
> > Note: that bug happened again today, on another RAID array. So the good
> > news
> > is that it is somewhat reproducible! The bad news, is that unless you
> > have a
> > magic solution, all my data are just lost (half of it was in the backup
> > pipe!)...
> >
> > Thanks for any help, and regards.
> > --
> > Pierre Vignéras
>
> It's not quite clear to me from the link whether your drives are
> truly toast, or not. If they are, then you are hosed. Assuming not, then
> you need to use
>
> `mdadm --examine /dev/sdxx` and `mdadm -Dt /dev/mdyy`
>
> to determine precisely all the parameters and the order of the block
> devices in the array. You need the chunk size, the superblock type, which
> slot was occupied by each device in the array (this may not be the same as
> when the array was created), the size of the array (if it did not fill the
> entire partition in every case), the RAID level, etc. Once you are certain
> you have all the information to enable you to re-create the array, if need
> be, the try to re-assemble the array with
>
> `mdadm --assemble --force /dev/mdyy`
>
> If it works, then fsck the file system. (I think I noticed you are
> using XFS. If so, do not use XFS_Check. Instead, use XFS_Repair with the
> -n option.) After you have a clean file system, issue the command
>
> `echo repair > /sys/block/mdyy/md/sync_action`
>
> to re-sync the array. If the array does not assemble, then you will
> need to stop it and re-create it using the options you obtained from your
> research above and adding the --assume-clean switch to prevent a resync if
> something is wrong. If the fsck won't work after re-creating the array,
> then you probably got one or more of the parameters incorrect.
