Using an lvm
manager that supports snapshotting (copy on write),
and periodically syncing ‘base’ volumes between hosts would
probably be the best way to manage this.
Downside is that you now have the overhead of snapshots, plus maintain a
full copy of the disk image on both machines involved. The benefit is that on migration, you
only need to transfer the cow snapshot which would typically be much smaller,
not a good option for, a fileserver for example, but a webserver
that has mostly static content would be an ideal candidate, where the changes
on a daily basis might only be in the 10’s of megabytes. As to a premade
tool to do this, there is none that I know of, but afaik
there is places to hook in to run such a script. Be aware, that even with a ‘fast’
method like this, you’ll probably extend the downtime considerably.
From:
xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Todd Deshane
Sent: January 19, 2008 12:15 AM
To: Andrew McCormack
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Xen Live
Migration
On Jan 10, 2008 1:42 PM, Andrew McCormack <merlinn@xxxxxxxxx> wrote:
I'm a little confused as to what I've found regarding Live
Migration. Is it true that there is a central file system accessible to
both hosts and that all that is transferred is the current MEMORY contents of
the domain?
That is the basic idea yes.
If this is true, is there no way to physically transfer the
domain file system from one host to another? Thanks.
In theory this could be done, but would require a lot more overhead. I can't
recall if there is any work with Xen on this or not. I believe OpenVZ, which
virtualizes at a layer higher (the operating system), has support for live
migration without the central file system.
Regards,
Todd
-Andrew
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