[ovirt-users] oVirt & gluster - which copy is written to?

[Alexander Wels]

On Thursday, May 12, 2016 12:05:22 AM Bill Bill wrote:
> Hello,
> 
> Let’s say I have a 5 node converged cluster of oVirt & glusterFS with a
> replica count of “3”.
 
> Host1 - replica
> Host2 - replica
> Host3 - replica
> Host4
> Host5
> 
> If I spin a VM up on Host1 – does the first replica get created local to
> that server?
 
> In the event I move the VM to another host, does the replica of the disk
> follow the VM so essentially it’s writing to a local copy first or does it
> “always” write across the network.
 
> For example, with VMware, the disk will follow the VM to the hypervisor you
> move it to so that the writes are essentially “local”.
 
> I have not been able to find anything on the internet or in the
> documentation that specifies how this process works. Ideally, you wouldn’t
> want a VM residing on Host1 that accesses its disk on Host3. Multiple that
> by hundreds of VM’s and it would create a ton of unnecessary network
> congestion.
 
While I cannot answer your actual question as I don't know enough about the 
internal implementation of how oVirt interacts with gluster. I just want to 
point out major difference between oVirt and VMWare. In oVirt storage domains 
are attached to data centers, not hosts. So there is no does the disk move 
from host1 to host2. The disk is on the storage domain and host1 and host2 and 
every other host in the data center has access to the storage domain.