In a process to restore a data volume in a first memory, a virtual point-in-time
(PIT) copy of the data volume is created. Creating the virtual PIT copy includes
creating first, second and third maps in memory. Each of the first, second, and
third maps includes a plurality of multi-bit entries. Each of the entries of the
first and second maps corresponds to a respective memory region of the first memory,
while each of the entries of the third map corresponds to a respective memory region
of a second memory for storing data of the virtual PIT copy.
