5.9. Migration

The Red Hat Enterprise Virtualization Manager uses migration to enforce load balancing policies for a cluster. Virtual machine migration takes place according to the load balancing policy for a cluster and current demands on hosts within a cluster. Migration can also be configured to automatically occur when a host is fenced or moved to maintenance mode. The Red Hat Enterprise Virtualization Manager first migrates virtual machines with the lowest CPU utilization. This is calculated as a percentage, and does not take into account RAM usage or I/O operations, except as I/O operations affect CPU utilization. If there are more than one virtual machines with the same CPU usage, the one that will be migrated first is the first virtual machine returned by the database query run by the Red Hat Enterprise Virtualization Manager to determine virtual machine CPU usage.

Virtual machine migration has the following limitations by default: See https://access.redhat.com/solutions/744423 for more details about tuning migration settings.