Xen users - Oct 2010 - Keeping domU configs sync''ed across nodes in a cluster

Hi all,

  I''ve got a Fedora 13 cluster (just two nodes) with Xen 4.0.1 and the
dom0''s are 2.6.32 kernel. I can live migrate the domU VMs back and
forth
just fine.

  The trick is that, until a VM has been migrated to the second node (or
I run ''virsh dumpxml domain > domain.xml; <copy to other
node>; virsh
define domain.xml), the second node doesn''t know that the domU exists.
So if the original node dies, I can''t (easily) recover the domU on the
backup. Also, if I make changes to the virtual hardware on one node, the
other node''s config goes stale.

  Is there a way to keep the domU configuration in sync across nodes? I
think I saw something to this effect a little earlier, but so far my
google-fu has not turned up anything.

Thanks!

Digimer

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On Wednesday 20 October 2010 05:30:01 Digimer wrote:
> Hi all,
> 
>   I''ve got a Fedora 13 cluster (just two nodes) with Xen 4.0.1 and
the
> dom0''s are 2.6.32 kernel. I can live migrate the domU VMs back and
forth
> just fine.
> 
>   The trick is that, until a VM has been migrated to the second node (or
> I run ''virsh dumpxml domain > domain.xml; <copy to other
node>; virsh
> define domain.xml), the second node doesn''t know that the domU
exists.
> So if the original node dies, I can''t (easily) recover the domU on
the
> backup. Also, if I make changes to the virtual hardware on one node, the
> other node''s config goes stale.
> 
>   Is there a way to keep the domU configuration in sync across nodes? I
> think I saw something to this effect a little earlier, but so far my
> google-fu has not turned up anything.
> 
> Thanks!
> 
> Digimer
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
How about just having cron export the xml files and using rsync (or plain ssh) 
to copy the files around?


B.

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i use csync2 for this job

Am 20.10.10 12:34, schrieb Bart Coninckx:
> On Wednesday 20 October 2010 05:30:01 Digimer wrote:
>> Hi all,
>>
>>    I''ve got a Fedora 13 cluster (just two nodes) with Xen
4.0.1 and the
>> dom0''s are 2.6.32 kernel. I can live migrate the domU VMs back
and forth
>> just fine.
>>
>>    The trick is that, until a VM has been migrated to the second node
(or
>> I run ''virsh dumpxml domain>  domain.xml;<copy to other
node>; virsh
>> define domain.xml), the second node doesn''t know that the domU
exists.
>> So if the original node dies, I can''t (easily) recover the
domU on the
>> backup. Also, if I make changes to the virtual hardware on one node,
the
>> other node''s config goes stale.
>>
>>    Is there a way to keep the domU configuration in sync across nodes?
I
>> think I saw something to this effect a little earlier, but so far my
>> google-fu has not turned up anything.
>>
>> Thanks!
>>
>> Digimer
>>
>> _______________________________________________
>> Xen-users mailing list
>> Xen-users@lists.xensource.com
>> http://lists.xensource.com/xen-users
>
> How about just having cron export the xml files and using rsync (or plain
ssh)
> to copy the files around?
>
>
> B.
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>
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I use OCFS2, a cluster-aware filesystem, to make config files available
on all of the nodes in my clusters of Xen hosts.  I have four separate
clusters of Xen servers, each with its own OCFS2 filesystem that is
mounted on all of the nodes in the cluster.  On some of them, I also
store disk files on this filesystem, but on others it serves no purpose
other than to store config files.  Of course, you need some cluster
storage or something like that, but even DRBD could be used to
synchronize a small partition or volume on each of the hosts with OCFS2,
GFS, etc.

-Nick

On Tue, 2010-10-19 at 23:30 -0400, Digimer wrote:
> Hi all,
> 
>   I''ve got a Fedora 13 cluster (just two nodes) with Xen 4.0.1 and
the
> dom0''s are 2.6.32 kernel. I can live migrate the domU VMs back and
forth
> just fine.
> 
>   The trick is that, until a VM has been migrated to the second node (or
> I run ''virsh dumpxml domain > domain.xml; <copy to other
node>; virsh
> define domain.xml), the second node doesn''t know that the domU
exists.
> So if the original node dies, I can''t (easily) recover the domU on
the
> backup. Also, if I make changes to the virtual hardware on one node, the
> other node''s config goes stale.
> 
>   Is there a way to keep the domU configuration in sync across nodes? I
> think I saw something to this effect a little earlier, but so far my
> google-fu has not turned up anything.
> 
> Thanks!
> 
> Digimer
> 
> 


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Since I''m generally using a dedicated iet iSCSI SAN when I use XEN, I
usually just create a NFS share on the OS partition of the SAN for the xen
configs, and mount that on all the dom0''s at /etc/xen.

Best Regards,
Nathan Eisenberg


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