[nSLUG] XEN & Heartbeat

Oliver Baltzer oliver at hytek.org
Tue Jun 2 23:08:55 ADT 2009


Hatem Nassrat wrote:
> On Tue, Jun 2, 2009 at 10:35 PM, Oliver Baltzer <oliver at hytek.org> wrote:
>> If you actually know in advance that one of your physical machines will
>> go away, you can migrate the running VM from one system to the another
>> online. I have never done this with Xen, but you might even be able to
> 
> Slightly offtopic, but which Virtualization Systems allow you to move
> VM's while keeping them online?

AFAIK VMWare ESX and KVM. ESX has a whole bunch of infrastructure for
doing these kinds of things. KVM lets you take a snapshot of the VM,
which you can then migrate onto a different system and revive there as
if nothing happened. If you can also teach your network hardware to send
all packets to the new host you can even keep TCP connections alive. Of
course the KVM solution is rather hack-ish and in fact the VM is going
to be gone for a moment, but if that happens before any TCP connection
times out, you would not notice anything on the client except a small
delay. When using something like DRBD or a multi-path SAN, such move
should be relatively quick as you do not need to copy the snapshot to a
different system, you just need to load it into memory of the new host.

I have no experience with Xen, but I suspect it is similar.

Oliver





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