Patent ID: 7266653

Claim:
A method for storing data in a data storage system that includes primary and secondary storage subsystems, including respective first and second volatile cache memories and respective first and second non-volatile storage media, the method comprising: receiving the data at the primary storage subsystem from a host processor; writing the data to the first volatile cache memory in the primary storage subsystem; copying the data from the primary storage subsystem to the secondary storage subsystem; writing the copied data to the second volatile cache memory in the secondary storage subsystem; returning an acknowledgment from the secondary storage subsystem to the primary storage subsystem responsively to writing the copied data to the second volatile cache memory and prior to saving the data in the second non-volatile storage media; signaling the host processor that the data have been stored in the data storage system responsively to the acknowledgment from the secondary storage subsystem; and transferring the data in the primary and secondary storage subsystems from the first and second volatile cache memories to the first and second non-volatile storage media, respectively.