Re: How to recreate a dmraid RAID array with mdadm

[Neil Brown <neilb@suse.de>]

On Thu, 18 Nov 2010 00:10:50 -0500
Mike Viau <viaum@sheridanc.on.ca> wrote:

> 
> > On Thu, 18 Nov 2010 14:17:18 +1100 <neilb@suse.de> wrote:
> > >
> > > > On Thu, 18 Nov 2010 13:32:47 +1100  wrote:
> > > > > ./mdadm -Ss
> > > > >
> > > > > mdadm: stopped /dev/md127
> > > > >
> > > > >
> > > > > ./mdadm -Asvvv
> > > > >
> > > > > mdadm: looking for devices for further assembly
> > > > > mdadm: no RAID superblock on /dev/dm-3
> > > > > mdadm: /dev/dm-3 has wrong uuid.
> > > > > want UUID-084b969a:0808f5b8:6c784fb7:62659383
> > > > > Segmentation fault
> > > >
> > > > Try this patch instead please.
> > >
> > > Applied new patch and got:
> > >
> > > ./mdadm -Ss
> > >
> > > mdadm: stopped /dev/md127
> > >
> > >
> > > ./mdadm -Asvvv
> > > mdadm: looking for devices for further assembly
> > > mdadm: no RAID superblock on /dev/dm-3
> > > mdadm: /dev/dm-3 has wrong uuid.
> > >  want UUID-084b969a:0808f5b8:6c784fb7:62659383
> > >  tst=0x10dd010 sb=(nil)
> > > Segmentation fault
> >
> > Sorry... I guess I should have tested it myself..
> >
> > The
> > if (tst) {
> >
> > Should be
> >
> > if (tst && content) {
> >
> 
> Apply update and got:
> 
> mdadm: /dev/sdb is identified as a member of /dev/md/imsm0, slot -1.
> mdadm: /dev/sda is identified as a member of /dev/md/imsm0, slot -1.
> mdadm: added /dev/sda to /dev/md/imsm0 as -1
> mdadm: added /dev/sdb to /dev/md/imsm0 as -1
> mdadm: Container /dev/md/imsm0 has been assembled with 2 drives
> mdadm: looking for devices for /dev/md/OneTB-RAID1-PV

So just to clarify.

With the Debian mdadm, which is 3.1.4, if you

 mdadm -Ss
 mdadm -Asvv

it says (among other things) that /dev/sda has wrong uuid.
and doesn't start the array.

But with the mdadm you compiled yourself, which is also 3.1.4,
if you

  mdadm -Ss
  mdadm -Asvv

then it doesn't give that message, and it works.

That is very strange.   It seems that the Debian mdadm is broken somehow, but
I'm fairly sure Debian hardly changes anything - they are *very* good at
getting their changes upstream first.

I don't suppose you have an /etc/mdadm.conf as well as /etc/mdadm/mdadm.conf
do you?  If you did and the two were different, the Debian's mdadm would
behave a bit differently to upstream (they prefer different config files) but
I very much doubt that is the problem.

But I guess if the self-compiled one works (even when you take the patch
out), then just
   make install

and be happy.

NeilBrown


> 
> 
> Full output at: http://paste.debian.net/100103/
> expires: 
> 
> 2010-11-21 06:07:30
> -M
> 
> 
>