Cold migration is the migration of turned-off or suspended virtual machines. With cold migration, you can move the associated disks from one datastore to another. The virtual machines are not required to be on shared storage. You can also use cold migration to move virtual machines from one datacenter to another.

You must turn off or suspend the virtual machines to migrate before you begin the cold migration process. Migrating a suspended virtual machine is considered a cold migration because although the virtual machine is turned on, it is not running.

If the virtual machine is turned off and configured with a 64-bit guest operating system, vCenter Server generates a warning if you try to migrate it to a host that does not support 64-bit operating systems. Otherwise, CPU compatibility checks do not apply when you migrate turned off virtual machines with cold migration.

When you migrate a suspended virtual machine, the new host for the virtual machine must meet CPU compatibility requirements, because the virtual machine must be able to resume executing instructions on the new host.

A cold migration consists of the following tasks:

  1. If you select the option to move to a different datastore, the configuration files, including the NVRAM file (BIOS settings), log files, and the suspend file, are moved from the source host to the destination host’s associated storage area. You can chose to move the virtual machine's disks, as well.

  2. The virtual machine is registered with the new host.

  3. After the migration is completed, the old version of the virtual machine is deleted from the source host if you selected the option to move to a different datastore.