Novell SUSE LINUX ENTERPRISE DESKTOP 11 SP1 - 8-18-2010 VIRTUALIZATION WITH ZEN Manual page 53

5.6.3 Migrating VM Guest Systems
The actual migration of the VM Guest system is done with the command:
xm migrate --live <domain_name> <host>
The option --live must be set to migrate a system that is currently running.
The speed of the migration depends on how fast the memory print can be saved to disk,
sent to the new VM Host Server and loaded there. This means, that small VM Guest
systems can be migrated faster than big systems with a lot of memory.
Managing a Virtualization Environment 43