Patent ID: 8478725

Claim:
A method for migrating persistent data associated with a virtual machine (VM), the method comprising: copying static persistent data from a source data store to a target data store, the static persistent data being persistent data associated with the VM that is not accessible by guest software; creating a new VM using the copied static persistent data: copying a virtual disk associated with the VM from the source data store to the target data store, wherein dynamic persistent data includes the virtual disk; monitoring input and output (I/O) disk operations during the copying of the virtual disk, the monitoring including maintaining a data structure identifying each disk block written to by the VM during the copying of the virtual disk, wherein disk blocks that are written to are dirty disk blocks; iteratively copying dirty disk blocks until a set of dirty blocks is smaller than a threshold number of disk blocks; and after the set of dirty blocks is smaller than the threshold number of disk blocks, stunning the VM, copying remaining dirty disk blocks to the target data store, and when all the persistent data of the VM has been copied to the target data store, resuming execution of the VM using persistent data stored on the target data store.