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From Paul Angus <>
Subject RE: System VMs not migrating when host down
Date Wed, 14 Feb 2018 09:14:33 GMT
Hi Sean,

The 'problem' with VM HA in KVM is that it relies on the parent host agent to be connected
to report that the VM is down.  We cannot assume that just because a host agent is disconnected,
that the VMs on that host are not running. 

This is where HOST HA comes in, this feature detects loss of connection to the agent and then
tries to determine if the VMs on that host are active and then attempts some corrective action.

Kind regards,

Paul Angus

53 Chandos Place, Covent Garden, London  WC2N 4HSUK

-----Original Message-----
From: Sean Lair [] 
Sent: 13 February 2018 23:06
Subject: System VMs not migrating when host down

Hi all,

We are testing VM HA and are having a problem with our system VMs (secondary storage and console)
not being started up on another host when a host fails.

Shouldn't the system VMs be VM HA-enabled?  Currently they are just in an "Alert" agent state,
but never migrate.  We are currently running 4.9.3.

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