A storage system and method for storing delta difference data indicative of the
differences between new data and old data. A data transferring unit has copies
of old data and new data. The data transferring unit compares the new data with
the old data to determine delta difference data indicative of the differences between
the new data and the old data. A target storage device having a copy of the old
data receives the delta difference data from the data transferring unit. The target
storage device stores the delta difference data and may then determine the new
data by merging the old data with the delta difference data. The target storage
device transmits the determined new data to a data receiving unit upon request.
The method and system may be used with peer-to-peer remote copy (PPRC) storage
system and storage area network (SAN) storage system.
