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Re: [Xen-users] Some HVM Live Migration Issues

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Subject: Re: [Xen-users] Some HVM Live Migration Issues
From: Javier Guerra Giraldez <javier@xxxxxxxxxxx>
Date: Tue, 23 Oct 2007 17:34:22 -0500
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On Tuesday 23 October 2007, Christian Horn wrote:
> > 1. Do I need a cluster file system in this kind of a setup? No 2 domUs
> > will access a LUN simultaneously from different nodes. This setup is
> > just to facilitate domU migration.
> In my opinion you need a lvm-software that is aware of multiple nodes
> accessing the volumes, like clvm or evms.

'plain' LVM is supposed to work on your setup, but only as long as you don't 
do any modification to the LVM metadata.  that is, you can't resize an LV, 
add/remove PV's, migrate data, etc.

to get around that limitations, you either use CLVM (or EVMS-HA), or shut down 
all-but-one boxes to do any change.

> > 2.  I have 2 LVM logical volumes: /dev/vms/winxp and /dev/vms/centos5.
> > I am able to create and run HVM domUs from either nodes without
> > issues. Live Migration does not work the first time from Node1 ->
> > Node2 or from Node2 -> Node 1. But if I create the XP domain once on
> > Node1, shut it down, then create it once more on Node 2 and then
> > migrate, it works. Really weird, but this is how it is. Looking at the
> > logs, everything looks fine. Just that the domain won't start after it
> > has migrated the first time. I think there is an issue initializing
> > the iscsi LUN in some way or the other.... but I can't make out.
> Could be a result of the need of a different lvm-implementation.

this is the first thing you should check: those LVs must be accessible with 
exactly the same names from both boxes


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