<div dir="ltr"><span style="font-family:arial,sans-serif;font-size:13px">"Instead, have the HA hypervisor layer </span><span style="font-family:arial,sans-serif;font-size:13px">protect the VM as a clustered service"</span><br>
<div><span style="font-family:arial,sans-serif;font-size:13px"><br></span></div><div style><span style="font-family:arial,sans-serif;font-size:13px">I had to read this a couple of times Lars, and it's interesting. If I understand correctly</span></div>
<div style><span style="font-family:arial,sans-serif;font-size:13px">run the cluster on bare metal, taking care of the virtual machine instances on the same</span></div><div style><span style="font-family:arial,sans-serif;font-size:13px">box?</span></div>
<div style><span style="font-family:arial,sans-serif;font-size:13px"><br></span></div><div style><span style="font-family:arial,sans-serif;font-size:13px">Kind Regards,</span></div><div style><span style="font-family:arial,sans-serif;font-size:13px"><br>
</span></div><div style><span style="font-family:arial,sans-serif;font-size:13px">Nick</span></div><div style><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Jul 17, 2014 at 5:48 AM, Lars Marowsky-Bree <span dir="ltr"><<a href="mailto:lmb@suse.com" target="_blank">lmb@suse.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="">On 2014-07-17T03:48:51, Alex Samad - Yieldbroker <<a href="mailto:Alex.Samad@yieldbroker.com">Alex.Samad@yieldbroker.com</a>> wrote:<br>
<br>
> I wonder if there Best practise or how to, on how to run clusters on say VMWare.<br>
<br>
</div>We've got many customers running SLE HA (pacemaker/corosync) cluster<br>
inside virtual machines. That works fine.<br>
<br>
There are a few obvious caveats. Make sure the VMs are actually running<br>
on different nodes being the most obvious one.<br>
<br>
Fencing is another. Typically these environments have shared storage, or<br>
can easily get it via iSCSI (and even easily get 3 devices), so we<br>
recommend the use of "sbd" for fencing.<br>
<br>
That - sort of - also implies a network-based quorum that is richer than<br>
merely being able to ping a node.<br>
<br>
There are some other concerns that are harder to address. We've seen VMs<br>
"freeze" when the hypervisor deems to take a snapshot or during live<br>
migration. You don't want that to affect the cluster; so set the<br>
corosync token timeout to an appropriate value.<br>
<br>
<br>
In general, if you can, it makes more sense to run HA closer to the<br>
hardware and not inside the VM - instead, have the HA hypervisor layer<br>
protect the VM as a clustered service. That has many advantages from an<br>
architectural and reliability perspective, not the least of which is<br>
that then HA becomes available for *all* VMs if needed, and the folks<br>
managing their virtualized service don't have to worry about HA<br>
themselves.<br>
<br>
Unfortunately, a few customers have choosen hypervisors whose idea of<br>
"HA" and "IO isolation" makes me weep, so they're stuck with running HA<br>
inside their VMs. I consider this a blatant failure of the HVM.<br>
<br>
<br>
Regards,<br>
Lars<br>
<span class="HOEnZb"><font color="#888888"><br>
--<br>
Architect Storage/HA<br>
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB 21284 (AG Nürnberg)<br>
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde<br>
</font></span><div class="HOEnZb"><div class="h5"><br>
<br>
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