Xen users - Dec 2005 - Centos + Xen 3.0 + Root on md = bad

Howdy folks,



I''m trying to boot Xen 3.0 on a Centos 4(.2) system with root
on a software raid1 volume.  When booting the Xen kernel,
''raidautorun'' in
the /init nash script fails to assemble either the root md or the raid5 md
containing my LVM volumes.



If I move root to /dev/hda1, the system boots
fine.  raidautorun still fails to assemble the md devices, but mdadm later
on in the boot process works just fine.



I see what looks like a similar
problem reported in May of this year with Xen 2.0.something.  Does this continue
to be a known problem?  I''m going to try adding mdadm to the initrd and
see
if replacing ''raidautorun'' with ''mdadm --assemble
--scan'' solves the problem,
but I''m curious if there are other solutions.



Thanks,



  -- Lars



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Hey Lars,

I had the same problem. Fixed it with compiling the RAID modules
in (CONFIG_MD_*).

See:
http://marc.theaimsgroup.com/?l=xen-users&m=113439862419211&w=2

larsks.21230602@bloglines.com wrote:
> I''m trying to boot Xen 3.0 on a Centos 4(.2) system with root
> on a software raid1 volume.  When booting the Xen kernel,
''raidautorun'' in
> the /init nash script fails to assemble either the root md or the raid5 md
> containing my LVM volumes.
> 
> 
> 
> If I move root to /dev/hda1, the system boots
> fine.  raidautorun still fails to assemble the md devices, but mdadm later
> on in the boot process works just fine.
> 
> 
> 
> I see what looks like a similar
> problem reported in May of this year with Xen 2.0.something.  Does this
continue
> to be a known problem?  I''m going to try adding mdadm to the
initrd and see
> if replacing ''raidautorun'' with ''mdadm
--assemble --scan'' solves the problem,
> but I''m curious if there are other solutions.
> 
> 
> 
> Thanks,
> 
> 
> 
>   -- Lars
> 
> 
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users

-- 
   Taneli Leppä         | Crasman Co Ltd
   <taneli@crasman.fi>  | <http://www.crasman.fi/>

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> I had the same problem. Fixed it with compiling the RAID modules
> in (CONFIG_MD_*).


Taneli,



Thanks for the information.



That gives me two other questions:



(1) This is for the folks at Xensource responsible for the binary distribution
-- if md support under Xen requires the md drivers to be compiled into the
kernel, why does the binary distribution from Xensource have them built as
modules?



(2) I''ve tried adding mdadm to the initrd, and it complains that
/dev/md0 and /dev/md1 don''t exist.  In fact, they *do* exist on the
initrd
filesystem *prior* to starting udev; after udev starts I''m not positive
(didn''t
have much time to fiddle with it this morning).  Even running mdadm with
--auto=yes
fails to create the device nodes.  *Should* this work?  Or is it simply not
possible to use the md drivers built as modules under the Xen kernel?



Thanks,



  -- Lars



_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

larsks.21230602@bloglines.com wrote:
>> I had the same problem. Fixed it with compiling the RAID modules
>>     
>
>   
>> in (CONFIG_MD_*).
>>     
>
>
>
> Taneli,
>
>
>
> Thanks for the information.
>
>
>
> That gives me two other questions:
>
>
>
> (1) This is for the folks at Xensource responsible for the binary
distribution
> -- if md support under Xen requires the md drivers to be compiled into the
> kernel, why does the binary distribution from Xensource have them built as
> modules?
>
>
>
> (2) I''ve tried adding mdadm to the initrd, and it complains that
> /dev/md0 and /dev/md1 don''t exist.  In fact, they *do* exist on
the initrd
> filesystem *prior* to starting udev; after udev starts I''m not
positive (didn''t
> have much time to fiddle with it this morning).  Even running mdadm with
--auto=yes
> fails to create the device nodes.  *Should* this work?  Or is it simply not
> possible to use the md drivers built as modules under the Xen kernel?
>
>   
I''ve been running Centos 4.x with Xen 2.0.7 and md raid1 based root
partitions for a while now. A couple of tips.

1. Double check that the Xen supplied kernel has all of the other
modules you need. It was missing the modules for the extra PCI IDE cards
I use.

2. Make your own initrd using the supplied mkinitrd command. It should
sort out all of the module and raid issues. Couldn''t ever boot with the
Xen supplied initrd files if I had raid partitions.

I''ll be interested to hear how you go as I haven''t upgraded my
Xen 2.0.7
environment yet as for the moment it is quite stable and I don''t want
the downtime. Perhaps in the new year.

Steve

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Hi again,

larsks.21230602@bloglines.com wrote:
> That gives me two other questions:
> (1) This is for the folks at Xensource responsible for the binary
distribution
> -- if md support under Xen requires the md drivers to be compiled into the
> kernel, why does the binary distribution from Xensource have them built as
> modules?
I believe they expected them to work - and they should work.
But they don''t, for some reason. :-)
> (2) I''ve tried adding mdadm to the initrd, and it complains that
> /dev/md0 and /dev/md1 don''t exist.  In fact, they *do* exist on
the initrd
> filesystem *prior* to starting udev; after udev starts I''m not
positive (didn''t
> have much time to fiddle with it this morning).  Even running mdadm with
--auto=yes
> fails to create the device nodes.  *Should* this work?  Or is it simply not
> possible to use the md drivers built as modules under the Xen kernel?
Yeah, I believe it has something to do with either udev or
the modules themselves. All RAID autorun requires is a simple
ioctl() call to the md driver, but it''s returning ENODEV. The
compiling in of modules is a good enough solution for me, so
I haven''t looked more into this.

-- 
   Taneli Leppä         | Crasman Co Ltd
   <taneli@crasman.fi>  | <http://www.crasman.fi/>

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