Re: raid10 issues after reorder of boot drives.

[NeilBrown <neilb@xxxxxxx>]

On Tue, 1 May 2012 10:45:08 +0100 Brian Candler <B.Candler@xxxxxxxxx> wrote:

> On Sat, Apr 28, 2012 at 08:03:55AM +1000, NeilBrown wrote:
> > I'm afraid you've been bitten by a rather nasty bug which is present in 3.3
> > and got back ported to some -stable kernel.  The fix has been submitted and
> > should be appearing in -stable kernels soon (maybe already).
> 
> Do you happen to know if this bug was present in ubuntu 11.10, kernel
> versions 3.0.0-15-server or 3.0.0-16-server ?

I don't keep track of what ubuntu (or anyone but suse) put in their kernels,
sorry.

> 
> I saw failures to assemble RAID6 arrays after unclean shutdowns on both of
> these, just in test environments.  If it happens again I'll send mdadm
> --examine output. I just tried to replicate it and failed :-(

To replicate:

 - create an array.
 - stop the array
 - assemble the array with at least one missing device e.g.:
    mdadm -A /dev/md0 /dev/sda1 /dev/sdb1
   if it was a 3-device array
 - check in /proc/mdstat that it is listed as "inactivate"
 - reboot
 - now "mdadm -E" the devices.  If the raid level is -unknown- then the bug
   has hit.

NeilBrown


> 
> Regards,
> 
> Brian.
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