METHOD AND APPARATUS FOR CREATING A VIRTUAL DATA COPY

摘要

Disclosed is a method for creating a virtual copy of data stored in a first memory. The virtual copy of data stored in the first memory is created in a second memory in response to a request to create a copy of all data stored in the first memory. Creating the virtual copy includes, in one embodiment, creating first and second tables in memory each one of which comprises a plurality of multibit entries. Each entry of the first table corresponds to a respective memory region of the first memory. Each entry of the second table corresponds to a respective memory region of the second memory. Each first bit of the first table indicates whether the corresponding memory region of the first memory contains valid data. Each second bit of the second table indicates whether data in the corresponding memory region the fist memory has been modified since the first table was created. Each first bit of the second table indicates whether the corresponding memory region of the second memory has been modified since the second table was created. Additionally, using the present invention more that one virtual copy of data stored in the first memory can be created at a time. Further, using the present invention, a virtual copy of the virtual copy can be created.