8:29 p.m.
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On 16/01/15 19:26, Mario Giammarco wrote:
2015-01-16 12:37 GMT+01:00 Simone Tiraboschi <stirabos(a)redhat.com
<mailto:stirabos@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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<div class="moz-cite-prefix">On 16/01/15 19:26, Mario Giammarco
wrote:<br>
</div>
<blockquote
cite="mid:CABQ2P6GF92-ZuOOZAv3Gu98wg-0VM_JStV98N8j68DixADnCog@mail.gmail.com"
type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">2015-01-16 12:37 GMT+01:00 Simone
Tiraboschi <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:stirabos@redhat.com"
target="_blank">stirabos@redhat.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"><span
class=""><br>
</span>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?<br>
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.<br>
<br>
</blockquote>
</div>
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?<br>
</div>
</div>
<br>
</blockquote>
<br>
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) <b>cannot</b> be running on more
than one host to avoid screwing its own storage volume (ie
heartbeat/fencing).<br>
<br>
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"!<br>
<br>
Cheers<br>
<br>
Alex<br>
<br>
<br>
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