Tijl Van den Broeck wrote:
> For the answers I start from the point of view of hearbeat 2
> (www.linux-ha.org). I do not know about commercial cluster products
> supporting Xen. Crossposting this to linux-ha mailing list as they can
> correct me on possible mistakes :-)
>
> On 3/28/07, Carl Caum <[EMAIL PROTECTED]> wrote:
>> Hello all. I have two servers with Xen running. I also have a SAN
>> that hold the virtual machines. I need to know if a few things are
>> possible.
>>
>> 1) I need to know if failover is possible and how is the best way to
>> accomplish this? Is it possible to have one dom0 take snapshots of
>> the other dom0 and restore the VMs from the other dom0 if it suddenly
>> stops responding?
>
> In theory yes, if you wrote your own necessary external plugins for
> doing so. But I presume you don't want to go through those troubles as
> there already is a native Xen OCF Resource Agent in the heartbeat
> project. A good explanation & demonstration for it can be found in the
> "SUSE Linux Enterprise Server 10 - Exploring the High-Availability
> Storage Foundation" presentation from september 2006, more
> specifically pages 137-142. It should also answer questions you might
> have. However if you really want to reinvent the wheel, please stick
> to the guidelines mentioned in the linux-ha wiki.
>
>>
>> 2) Is it possible to have a VM do a live migrate to the other server
>> automatically if the current server it's running on is being shutdown
>> for maintenance.
>
> Live-migration is not yet included in the Xen OCF RA, only "migrate"
> is possible at the moment. Also do NOT trigger a live-migration
> yourself using "xm", as hb2 will think the resource crashed and will
> try to start it again which leads to ehm... data corruption to say at
> least :-)
>
>>
>> 3) Is it possible to cluster the two servers so they share CPU power
>> and memory resources between the two instances of xen. So really the
>> VMs are arbitrarily run on both servers simultaneously thus
>> increasing their speed. If this is possible, what happens if one of
>> the servers suddenly crashes?
>
> By this you mean... running the same machine in parallel, whilst
> sharing exclusive resources as such would be possible by an
> Active-Active cluster? This would not really be a Xen issue, rather a
> hb2 one with the use of a cluster filesystem, not everything can run
> in A-A mode I think (not an expert on this, check the linux-ha wiki
> for more info).
> To accomplish this, additionally to setting up hb2 between your
> dom0's, you'd also have to set it up between the domU's running inside
> the dom0's.
>
> There have been discussions on the linux-ha list about the Xen RA (and
> someone who was writing an alternative one for domU's specifically I
> think), I suggest you find 'm & read :-)
I _think_ that the live migration stuff is now in our development
version. But I'm not 100% sure of that ;-). If it is, then it'll show
up in a few weeks in a new version.
--
Alan Robertson <[EMAIL PROTECTED]>
"Openness is the foundation and preservative of friendship... Let me
claim from you at all times your undisguised opinions." - William
Wilberforce
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