Patent ID: 8527990

Claim:
A computer-implemented method for migrating virtual machines, at least a portion of the method being performed by a computing device comprising at least one processor, the method comprising: identifying a request to migrate a virtual machine from a primary site to a secondary site, wherein: the primary site comprises a primary storage device used for storage by the virtual machine; the primary storage device has been configured for asynchronous replication to a secondary storage device at the secondary site prior to identifying the request to migrate the virtual machine from the primary site to the secondary site; identifying a difference map that: reflects differences between data on the primary storage device and asynchronously replicated data on the secondary storage device; provides information for use in determining whether the asynchronously replicated data on the secondary storage device can be leveraged to fulfill input/output attempts from the virtual machine at the secondary site that are intercepted after the virtual machine has been initiated at the secondary site; initiating, before the primary storage device has been completely replicated to the secondary storage device, the virtual machine at the secondary site; intercepting at least one input/output attempt from the virtual machine at the secondary site to the secondary storage device; determining, based on the difference map, that a region indicated in the input/output attempt has not yet been synchronized from the primary storage device; retrieving the region from the primary storage device before allowing the input/output attempt to proceed.