Patent ID: 6996687

Claim:
A computer readable medium comprising instructions executable by a computer system, wherein the computer system implements a method in response to executing the instructions, the method comprising: creating a primary data volume; creating a first virtual copy of the primary data volume; modifying first data of the primary data volume after creation of the first virtual copy thereof; creating a second virtual copy of the primary data volume after modification of the first data thereof; generating a write-data transaction for modifying second data of the primary data volume, wherein the write-data transaction is generated after creation of the second virtual copy; copying the second data of the primary data volume to memory allocated to store data of the second virtual copy; modifying the second data of the primary data volume after the second data is copied to the memory allocated to store data of the second virtual copy; copying a third virtual copy of the primary data volume after modification of the second data thereof; wherein, before the second data of the primary volume is modified, the second data is copied only to the memory allocated to store data of the second virtual copy.