The present invention is a system and method that performs disk migration
in a virtual machine environment. The present invention quickly and
easily migrates a virtual machine from one host to another thus improving
flexibility and efficiency in a virtual machine environment for "load
balancing" systems, performing hardware or software upgrades, handling
disaster recovery, and so on. Certain of the embodiments are specifically
directed to providing a mechanism for migrating the disk state along with
the device and memory states, where the disk data resides in a remotely
located storage device that is common to multiple host computer systems
in a virtual machine environment. The virtual machine migration process,
which includes disk data migration, occurs without the user's awareness
and, therefore, without the user's experiencing any noticeable
interruption.