Patent ID: 7350042

Claim:
A method comprising: creating y virtual data volumes, wherein y is a number greater than 2, and wherein the y th virtual data volume is the most recently created of the y virtual data volumes, wherein the y virtual data volumes comprise y virtual copies, respectively, of a primary data volume; copying first data of the primary data volume to memory allocated to store data of the y th virtual data volume; modifying the first data of the primary data volume after the first data is copied to the memory allocated to store data of the y th virtual data volume; wherein, before the first data of the primary volume is modified, the first data is copied only to the memory allocated to store data of the y th virtual data volume; after the first data of the primary volume is modified, copying the first data from the memory allocated to store data of the y th virtual data volume to memory allocated to store data of one of the other y virtual data volumes in response to a generation of a write-data transaction for modifying data of the one of the other y virtual data volumes.