[Users] Asking for advice on hosted engine

[Giorgio Bersano]

Hello everybody,
I discovered oVirt a couple of months ago when I was looking for the
best way to manage our small infrastructure. I have read any document
I considered useful but I would like to receive advice from the many
experts that are on this list.

I think it worths an introduction (I hope doesn't get you bored).

I work in a small local government entity and I try to manage
effectively our limited resources.
We have many years of experience with Linux and especially with CentOS
which we have deployed on PC (i.e. for using as firewall in remote
locations) and moreover on servers.

We have been using Xen virtualization from the early days of CentOS 5
and  we have built our positive experience on KVM too.
I have to say that libvirt in a small environment like ours is really
a nice tool.
So nothing to regret.

Trying to go a little further, as already said, I stumbled upon oVirt
and I've found the project intriguing.

At the moment we are thinking of deploying it on a small environment
of four very similar servers each having:
- a couple of Xeon E5504
- 6 x 1Gb ethernet interfaces
- 40 GB of RAM
two of them have 72 GB of disk (mirrored)
two of them have almost 500GB of useful RAID array

Moreover we have an HP iSCSI storage that should easily satisfy our
current storage requirement.

So, given our small server pool, the necessity of another host just to
run the supervisor seems a requirement too high.

Enter "hosted engine" and the picture takes brighter colors. Well, I'm
usually not the adventurous guy but after experimenting a little with
oVirt 3.4 I developed better confidence.
We would want to install the engine over the two hosts with smaller disks.

For what I know, installing hosted engine mandates NFS storage. But we
want this to be highly available too, and possibly to have it on the
very same hosts.

Here is my solution: make a gluster replicated volume across the two
hosts and take advantage of that NFS server.
Then I put 127.0.0.1 as the address of the NFS server in the
hosted-engine-setup so  the host is always able to reach the storage
server (itself).
GlusterFS configuration is done outside of oVirt that, regarding
engine's storage, doesn't even know that it's a gluster thing.

Relax, we've finally reached the point where I'm asking advice :-)

Storage and virtualization experts, do you see in this configuration
any pitfall that I've overlooked given my inexperience in oVirt,
Gluster, NFS or clustered filesystems?
Do you think that not only it's feasable (I know it is, I made it and
it's working now) but it's also reliable and dependable and I'm not
risking my neck on this setup?

I've obviously made some test but I'm not at the confidence level of
saying that all is right in the way it is designed.

OK, I think I've already written too much, better I stop and humbly
wait for your opinion but I'm obviously here if any clarification by
my part  is needed.

Thank you very much for reading until this point.
Best Regards,
Giorgio.