US 7,552,282 Bl Jun. 23, 2009
(54) METHOD, COMPUTER READABLE
MEDIUM, AND DATA STORAGE SYSTEM
FOR SELECTIVE DATA REPLICATION OF
CACHED DATA
(75) Inventors: Michael Bermingham, Framingham,
MA (US); Kendell A. Chilton,
Southborough, MA (US); Robert
DeCrescenzo, Franklin, MA (US);
Mark J. Halstead, Watertown, MA
(US); Haim Kopylovitz, Newton, MA
(US); Steven T. McClure,
Northborough, MA (US); James M.
McGillis, Franklin, MA (US); Ofer E.
Michael, Newton, MA (US); Brett D.
Niver, Grafton, MA (US); John K.
Walton, Mendon, MA (US)
(73) Assignee: EMC Corporation, Hopkinton, MA (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 124 days.
Described are techniques for selective data replication. Cached data is replicated if it is characterized as critical. Critical data may include data associated with a write I/O operation. Cache locations are selected for replicated data so that a first location is mapped to a first memory board and a second location is mapped to a second memory board. Data for a read operation is not replicated in cache. Other noncache data that is critical and thus replicated includes metadata. Cache locations for data of read and write I/O operations are selected dynamically at the time the I/O operation is made from the same pool of cache locations.
19 Claims, 17 Drawing Sheets
