A method for migrating data between heterogeneous data storage devices within a storage area network is disclosed. A first virtualizer presents stored data as a first virtual disk, and then communicates a managed disk representation of the first virtual disk to a second virtualizer. After receiving the managed disk representation, the second virtualizer virtualizes the stored data from the managed disk representation as a second virtual disk. At such point, the stored data can be progressively migrated from the first virtualizer to the second virtualizer.