To add my voice to this; This is exactly what I do as well (though on
RHEL + RHCS/High-Availabiltiy Add-On):
https://alteeve.ca/w/AN!Cluster_Tutorial_2
As Lars said, it's a very portable solution as it will make any OS HA
without the user of the OS or any software in it being aware of the HA
components.
digimer
On 17/07/14 11:36 PM, Nick Cameo wrote:
"Instead, have the HA hypervisor layer protect the VM as a clustered
service"
I had to read this a couple of times Lars, and it's interesting. If I
understand correctly
run the cluster on bare metal, taking care of the virtual machine
instances on the same
box?
Kind Regards,
Nick
On Thu, Jul 17, 2014 at 5:48 AM, Lars Marowsky-Bree <l...@suse.com
<mailto:l...@suse.com>> wrote:
On 2014-07-17T03:48:51, Alex Samad - Yieldbroker
<alex.sa...@yieldbroker.com <mailto:alex.sa...@yieldbroker.com>> wrote:
> I wonder if there Best practise or how to, on how to run clusters
on say VMWare.
We've got many customers running SLE HA (pacemaker/corosync) cluster
inside virtual machines. That works fine.
There are a few obvious caveats. Make sure the VMs are actually running
on different nodes being the most obvious one.
Fencing is another. Typically these environments have shared storage, or
can easily get it via iSCSI (and even easily get 3 devices), so we
recommend the use of "sbd" for fencing.
That - sort of - also implies a network-based quorum that is richer than
merely being able to ping a node.
There are some other concerns that are harder to address. We've seen VMs
"freeze" when the hypervisor deems to take a snapshot or during live
migration. You don't want that to affect the cluster; so set the
corosync token timeout to an appropriate value.
In general, if you can, it makes more sense to run HA closer to the
hardware and not inside the VM - instead, have the HA hypervisor layer
protect the VM as a clustered service. That has many advantages from an
architectural and reliability perspective, not the least of which is
that then HA becomes available for *all* VMs if needed, and the folks
managing their virtualized service don't have to worry about HA
themselves.
Unfortunately, a few customers have choosen hypervisors whose idea of
"HA" and "IO isolation" makes me weep, so they're stuck with running HA
inside their VMs. I consider this a blatant failure of the HVM.
Regards,
Lars
--
Architect Storage/HA
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix
Imendörffer, HRB 21284 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar
Wilde
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Digimer
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What if the cure for cancer is trapped in the mind of a person without
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