A system for optimizing storage operations by operating only on mapped blocks may include a first and a second set of one or more storage devices, a virtual device client and a virtual device server. The virtual device server may be configured to aggregate storage in the first set of one or more storage devices into a virtual storage device, and make the virtual device accessible to the virtual device server. In preparation for a synchronization operation, the virtual device server may obtain a map identifying one or more in-use regions of the virtual storage device from the virtual device client. The virtual device server may then perform the synchronization operation by copying the one or more in-use regions of the virtual storage device to the second set of one or more storage devices.