On Mon, Nov 13, 2017 at 3:33 PM, Rudi Ahlers <rudiahlers@gmail.com> wrote:

Hi,

Can someone please give me some pointers, what would be the best setup for performance and reliability?

We have the following hardware setup:

3x Supermicro server with following features per server:
128GB RAM
4x 8TB SATA HDD
2x SSD drives (intel_ssdsc2ba400g4 - 400GB DC S3710)
2x 12 core CPU (Intel(R) Xeon(R) CPU E5-2650 v4 @ 2.20GHz
Quad port 10Gbe Inter NIC
2x 10GB Cisco switches (to isolate storage network from LAN)

One of the servers will be in another office, with a 600Mb wireless link for Disaster Recovery.

All 3 servers need to be on the same network with low latency between servers. Gluster volume is used in replica 3 configuration in oVirt, and data will be written to all 3 servers synchronously. If you have one of the 3 servers in a remote location, your writes will be slow and the storage will seem to be unavailable to oVirt.

For Disaster recovery, you can use gluster's geo-replication feature. This does need an additional server in the remote location. See https://www.ovirt.org/develop/release-management/features/gluster/gluster-dr/

What is recommended for the best setup in terms of redundancy and speed?

I am guessing GlusterFS with a Distributed Striped Replicated Volume across 3 of the servers.

Replica 3 gluster volume with sharding turned on for the gluster volume. If you use the deployment via Cockpit option, the volume is created with all recommended options.

You can also manually set this by enabling the virt profile, like this

# gluster volume set <volumename> group virt

For added performance I want to use the SSD drives, perhaps with dm-cache?

Should I combine the 4x HDD's using LVM on each host node?
What about RAID 6?

Gluster can work with either RAID or JBOD ( with replica 3, JBOD can be used, as gluster has the redundancy built in on the other nodes). Users often choose RAID to aggregate capacity from multiple disks as single brick, and also as the brick rebuilt time is offloaded to RAID layer in case of any of the hard disk failures. The answer is it depends on your needs and the hardware you have.

Virtual Machines will then reside on the oVirt Cluster and any one of the 3 host nodes can fail, or any single HDD can fail and all should still work, right/?

That's correct. With a replica 3 approach, the oVirt environment is available even when one of the 3 hosts fail.

--
Kind Regards
Rudi Ahlers
Website: http://www.rudiahlers.co.za

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