Migrating CPUs in an Active Domain

Following are the requirements and restrictions on CPUs when performing a migration.

• The source and target machines must have the same processor type running at the same frequency.

• The target machine must have sufficient free strands to accommodate the number of strands in use by the domain. In addition, full cores must be allocated for the migrated domain. If the number of strands in the source are less than a full core, the extra strands are unavailable to any domain until after the migrated domain is rebooted.

• After a migration, CPU dynamic reconfiguration (DR) is disabled for the target domain until it has been rebooted. Once a reboot has occurred, CPU DR becomes available for that domain.

• Either the source domain must have only a single strand, or the guest OS must support CPU DR, so that the domain can be shrunk to a single strand before migration. Conditions in the guest domain that would cause a CPU DR removal to fail would also cause the migration attempt to fail. For example, processes bound to CPUs within the guest domain, or processor sets configured in the source logical domain, can cause a migration operation to fail.