This article provides information on the types of virtual machine migration in the vCenter Server and ESX/ESXi environments and the impact of snapshots on migration.

There are three types of virtual machine migration:

• Cold Migration - Relocates the virtual machine files and registers the virtual machine when it is powered off.
• vMotion - Relocates the virtual machine's running state and registers the virtual machine when it is powered on.
• Storage vMotion - Relocates the virtual machine files when the virtual machine is powered on.
  

Impact of snapshots

vMotion

A powered-on virtual machine can be migrated to a different ESX host. In this case, all snapshots are retained when the virtual machine is vMotioned. However, the files comprising the virtual machine are not relocated. The virtual machine is unregistered from the source host and is registered to the destination host.

Cold Migration

A powered-off virtual machine can be migrated to a different ESX host and/or to a different datastore. When a virtual machine is migrated to a different datastore, files can be individually moved to different destinations. The virtual machine files, such as .vmsd, .vmsn, -delta.vmdk, and redologs, that support snapshot functionality are moved with the .vmx configuration file.

When a virtual machine is migrated between ESX hosts without changing datastores, the files remain untouched.

Storage vMotion

• Migration of powered-on virtual machines with snapshots cannot be performed in ESX/ESXi 3.x and ESX/ESXi 4.x. You must either delete the snapshots or power off the virtual machine before the migration.
• Migration of powered-on virtual machines with snapshots is supported in ESXi 5.0 and later.

Note: vMotion is supported in AppVols 2.10 and later. svMotion is not supported in View or AppVols.

• Understanding virtual machine snapshots in VMware ESXi and ESX (1015180)
• Migrating virtual machines with Raw Device Mappings (RDMs) (1005241)
• The Migrating Virtual Machines section in the vSphere Datacenter Administration Guide for your version of ESX