Hello Everyone,
Reading through the document:
"Red Hat Hyperconverged Infrastructure for Virtualization 1.5
 Automating RHHI for Virtualization deployment"

Regarding storage scaling,  i see the following statements:

2.7. SCALING
Red Hat Hyperconverged Infrastructure for Virtualization is supported for one node, and for clusters of 3, 6, 9, and 12 nodes.
The initial deployment is either 1 or 3 nodes.
There are two supported methods of horizontally scaling Red Hat Hyperconverged Infrastructure for Virtualization:

1 Add new hyperconverged nodes to the cluster, in sets of three, up to the maximum of 12 hyperconverged nodes.

2 Create new Gluster volumes using new disks on existing hyperconverged nodes.
You cannot create a volume that spans more than 3 nodes, or expand an existing volume so that it spans across more than 3 nodes at a time

2.9.1. Prerequisites for geo-replication
Be aware of the following requirements and limitations when configuring geo-replication:
One geo-replicated volume only
Red Hat Hyperconverged Infrastructure for Virtualization (RHHI for Virtualization) supports only one geo-replicated volume. Red Hat recommends backing up the volume that stores the data of your virtual machines, as this is usually contains the most valuable data.
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Also  in oVirtEngine UI, when I add a brick to an existing volume i get the following warning:

"Expanding gluster volume in a hyper-converged setup is not recommended as it could lead to degraded performance. To expand storage for cluster, it is advised to add additional gluster volumes." 

Those things are raising a couple of questions that maybe for some for you guys are easy to answer, but for me it creates a bit of confusion...
I am also referring to RedHat product documentation,  because I  treat oVirt as production-ready as RHHI is.

1. Is there any reason for not going to distributed-replicated volumes ( ie: spread one volume across 6,9, or 12 nodes ) ?
- ie: is recomanded that in a 9 nodes scenario I should have 3 separated volumes,  but how should I deal with the folowing question

2. If only one geo-replicated volume can be configured,  how should I deal with 2nd and 3rd volume replication for disaster recovery

3. If the limit of hosts per datacenter is 250, then (in theory ) the recomended way in reaching this treshold would be to create 20 separated oVirt logical clusters with 12 nodes per each ( and datacenter managed from one ha-engine ) ?

4. In present, I have the folowing one 9 nodes cluster , all hosts contributing with 2 disks each  to a single replica 3 distributed replicated volume. They where added to the volume in the following order:
node1 - disk1
node2 - disk1
......
node9 - disk1
node1 - disk2
node2 - disk2
......
node9 - disk2
At the moment, the volume is arbitrated, but I intend to go for full distributed replica 3.

Is this a bad setup ? Why ?
It oviously brakes the redhat recommended rules...

Is there anyone so kind to discuss on these things ? 

Thank you very much !

Leo 


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Best regards, Leo David




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Best regards, Leo David