I am assuming that it isn't on shared storage.
This tidbit from VMware vSphere 5.1 might be relevant to what you are looking for:
In vSphere 5.1 and later, vMotion does not require environments with shared storage. This is useful for performing cross-cluster migrations, when the target cluster machines might not have access to the source cluster's storage. Processes that are working on the virtual machine continue to run during the migration with vMotion.