Host fencing in oVirt - Fixing the unknown and allowing VMs to be highly available [Martin Peřina]
Channel: RedHatCzech
Date: 2016-02-15

In order to support highly available VMs, oVirt needs a mechanism to determine the status of a VM running on non-responsive host. We need to be sure that VM is not running before restarting it on a different host to prevent data corruption. And oVirt fencing flow is crucial to achieve this goal.

Host fencing flow is a part of oVirt host monitoring, it takes care of non-responsive hosts and tries to make them responsive again. We will describe each step of the whole fencing flow on real world issues, describe what actions around hosts/VMs are taken after each step of fencing flow and also describe how power management interface of the hosts is used.