Patent ID: 7330947

Claim:
A method of backing up data stored in a first virtual storage associated with a source physical storage into a backup medium, the source physical storage comprising a number of used blocks containing actual data and a number of unused blocks containing no actual data, the method comprising: identifying the used blocks containing actual data in the source physical storage; providing a second virtual storage associated with at least one physical storage, the second virtual storage being smaller than the first virtual storage and having a size corresponding to the number of used blocks containing actual data stored in the first virtual storage; creating an address correspondence table between one or more block addresses of the actual data in the first virtual storage and sequential block addresses in the second virtual storage; copying the actual data from the block addresses of the source physical storage to the sequential block addresses of the at least one physical storage in accordance with the created address correspondence tables; and backing up all the actual data from the at least one physical storage to the backup medium by copying all the block addresses of the at least one physical storage regardless of whether the block addresses of the at least one physical storage includes the actual data.