My current space usage excluding backups sits at about only 1TB so I figure 3-5 TB would be more than enough for VM storage only + some room to grow.  There will be around 24 linux VMs total but 80% of them are VERY low usage and low spec servers.

I've been considering a 3 host hyperconverged oVirt setup, replica 3 arbiter 1 setup with a disaster recovery plan to replicate the gluster volume to a separate server.  I would of course do additional incremental backups to an alternate server as well probably with rsync or some other method. 

Some questions:

1. Is it recommended to use SSDs for glusterFS or can the performance of regular server/sas drives be sufficient enough performance.  If using SSDs is it recommended to use enterprise SSDs are consumer SSDs good enough due to the redundancy of glusterFS?   I would love to hear of any use cases from any of you regarding hardware specs you used in hyperconverged setups and what level of performance you are seeing. 

2. Is it recommended to RAID the drives that form the gluster bricks?  If so what raid level? 

3. How do I calculate how much space will be usable in a replicate 3 arbiter 1 configuration?  Will it be 75% of total drive capacity minus what I lose from raid (if I raid the drives)? 

4. For replication of the gluster volume, is it possible for me to replicate the entire volume to a single drive/raid array in an alternate server or does the replicated volume need to match the configuration of the main glusterFS volume (i.e. same amount of drives/configuration etc). 

5. Has the meltdown bug caused or expected to cause major issues with oVirt hyperconverged setup due to performance loss from the patches.  I've been reading articles suggesting up to 30% performance loss on some converged/storage setups due to how CPU intensive converged setups are.   

Thanks in advance!