<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<br>
<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>
</body>
</html>