[Gluster-users] about HA infrastructure for hypervisors

Nathan Stratton nathan at robotics.net
Wed Jun 27 20:07:21 UTC 2012

On Wed, 27 Jun 2012, Brian Candler wrote:

> I've made a test setup like this, but unfortunately I haven't yet been able
> to get half-decent performance out of glusterfs 3.3 as a KVM backend.  It
> may work better if you use local disk for the VM images, and within the VM
> mount the glusterfs volume for application data.

What is considered half-decent? I have a 8 cluster distribute+replicate 
setup and I am getting about 65MB/s and about 1.5K IOPS. Considering that 
I am only using a single two disk SAS strip in each host I think that is 
not bad.

> Alternatively, look at something like ganeti (which by default runs on top
> of drbd+LVM, although you can also use it to manage a cluster which uses a
> shared file store backend like gluster)
> Maybe 3.3.1 will be better. But today, your investment in SSDs is quite
> likely to be wasted :-(
>> The idea is to have HA if either one KVM hypervisor or one Glusterfs
>> server stop working (failure, maintenance, etc).
> You'd also need some mechanism for starting each VM on node B if node A
> fails.  You can probably script that, although there are lots of hazards for
> the unwary.  Maybe better to have the failover done manually.

Also check out oVirt, it integrates with Gluster and provides HA.

>> 2. We still didn't decide what physical network to choose between FC, FCoE
>> and Infiniband.
> Have you ruled out 10G ethernet? If so, why?

I agree, we went all 10GBase-T.

> (note: using SFP+ ports, either with fibre SFP+s or SFP+ coax cables, gives
> much better latency that 10G over RJ45/CAT6)

Actually with the new switches like Arista this is less of an issue.

>> 3. Would it be better to split the Glusterfs namespace into two gluster
>> volumes (one for each hypervisor), each running on a Glusterfs server
>> (for the normal case where all servers are running)?
> I don't see how that would help - I expect you would mount both volumes on
> both KVM nodes anyway, to allow you to do live migration.


Nathan Stratton
nathan at robotics.net

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