Patent ID: 8239646

Claim:
A method for migrating a virtual machine disk (VM disk) from first physical storage to second physical storage while the virtual machine (VM) is running, the method comprising: taking a snapshot of the VM disk as represented by a first parent VM disk stored on the first physical storage, whereby a first child VM disk is created; copying the first parent VM disk to the second physical storage as a second parent VM disk while redirecting writes for the first parent VM disk to the first child VM disk; re-parenting the first VM child disk to the second parent VM disk; and consolidating the first child VM disk and the second parent VM disk; wherein changes during the consolidating of the first child VM disk and the second parent VM disk are captured by: (a) creating a second child VM disk; (b) redirecting writes for the first child VM disk to the second child VM disk during the consolidating; (c) re-parenting the second child VM disk to the second parent VM disk after the consolidating; and (d) performing a consolidation operation of the second child VM disk with the second parent VM disk.