[ovirt-users] Put the engine inside hosts after installation

[Alex Crow]

On 16/01/15 19:26, Mario Giammarco wrote:
>
>
> 2015-01-16 12:37 GMT+01:00 Simone Tiraboschi <stirabos at redhat.com 
> <mailto:stirabos at redhat.com>>:
>
>
>     HA capability is provided for other VMs by oVirt engine. But who
>     provide it if the engine itself is on a VM on the host that it's
>     managing?
>     HA for the Engine VM needs to be managed by the hosts and not the
>     Engine itself: so we have ovirt-hosted-engine-ha that ensure HA
>     for the engine VM, the engine cloud than provide HA for other VMs.
>
> I am surprised. I supposed that HA was "self provided" by the cluster 
> like in xenserver. So you tell me that is the engine that checks if 
> servers and vms are on like in cloudstack?
>

This is just how any VM self-hosted setup would work. The 
'engine/management' VM has to have HA managed by something other than 
the engine itself - otherwise if the engine is down how would it know or 
be able to restart itself? In VMWare or Xenserver there would have to be 
a separate system other than that in the engine VM to make sure that the 
management engine VM is a) running on at least one host on the cluster 
and b) *cannot* be running on more than one host to avoid screwing its 
own storage volume (ie heartbeat/fencing).

Then this "managed engine" only has to take care of keeping its own VMs 
up. Logically I cannot see any other way this could possibly work - see 
"chicken and egg"!

Cheers

Alex


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