Patent ID: 7831782

Claim:
A method comprising: creating first and second data volumes, wherein the second data volume is data consistent with the first data volume at time t 0 ; writing new first data to the first data volume at time t 1 , wherein t 1 is after time t 0 ; writing new second data to the first data volume at time t 2 , wherein t 2 is after time t 1 ; writing new third data to the second data volume at time t 3 , wherein t 3 is after time t 0 , wherein the second data volume is in a first data state before the new third data is written to the second data volume, wherein the second data volume is in a second data state after the new third data is written to the second data volume, and wherein the new third data is different from the new first data and the new second data; writing new fourth data to the second data volume at time t 4 , wherein t 4 is after time t 3 , wherein the second data volume is in the second data state before the new fourth data is written to the second data volume, wherein the second data volume is in a third data state after the new fourth data is written to the second data volume, and wherein the new fourth data is different from the new first data, the new second data, and the new third data; restoring the second data volume to the second data state at time t 5 , wherein time t 5 is after time t 4 ; restoring the second data volume to the first data state at time t 6 , wherein time t 6 is after time t 5 ; writing the new first data to the second data volume at time t 7 , wherein t 7 is after time t 6 ; writing the new second data to the second data volume at time t 8 , wherein t 8 is after time t 7 .