Richard V Mattson

54349923, Jul 18, 1995

Sep 4, 1992

7/940560

Richard L. Mattson - San Jose CA

International Business Machines Corporation - Armonk NY

G06F 1200
G06F 1300

395425

A method and means is disclosed for dynamically partitioning an LRU cache partitioned into a global cache storing referenced objects of k different data types and k local caches storing objects of a single type. Referenced objects are stored in the MRU position of the global cache and overflow is managed by destaging the LRU object from the global to the local cache having the same data type. Dynamic partitioning is accomplished by recursively creating and maintaining from a trace of objects an LRU list of referenced objects and associated data structures for each subcache, creating and maintaining a multi-planar array of partition distribution data from the lists and the trace as a collection of all possible of maximum and minimum subcache sizing, optimally resizing the subcache partitions by applying a dynamic programming heuristic to the multiplanar array, and readjusting the partitions accordingly.

54169151, May 16, 1995

Dec 11, 1992

7/989245

Richard L. Mattson - San Jose CA
Jaishankar M. Menon - San Jose CA

International Business Machines Corporation - Armonk NY

G06F 1116
G06F 1206

395425

A method and system for minimizing seek affinity and enhancing write sensitivity in a direct access storage device (DASD) array are disclosed. SEEK affinity and WRITE efficiency are preserved in which logical cylinders, as recorded on the DASD array, are managed as individual log structured files (LSF). Tracks or segments of data and parity blocks having the same or different parity group affinity and stored on the same or different DASD cylindrical addresses are written into a directory managed buffer. Blocks having the same parity affinity and written to counterpart cylinders are written out from the buffer to spare space reserved as part of each DASD cylinder. Otherwise, blocks are updated in place in their DASD array location.

52589846, Nov 2, 1993

Jun 13, 1991

7/714969

Jaishankar M. Menon - San Jose CA
Richard L. Mattson - San Jose CA
Spencer W. Ng - San Jose CA

International Business Machines Corporation - Armonk NY

G06F 1120

371 101

A method and means in which data and parity blocks forming parity groups together with spare blocks are distributed over array block locations according to at least one combinatorial design, each group having N data and P parity blocks. The combinatorial designs yield uniform or balanced loading thereby minimizing the number of accesses to reconstruct missing data and parity blocks and their copyback into spare block locations, and, minimize the number of accesses to the reconstructed data referenced subsequent to its copyback. Distributions of the spare block capacity of one or two DASDs are shown over single and multiple arrays and shared among multiple arrays. Parity block distribution although ancillary to spare distribution enhances throughput and reduces the number of accesses for rebuild etc.

59372052, Aug 10, 1999

Dec 6, 1995

8/568327

Richard Lewis Mattson - Pacific Grove CA
Jaishankar Moothedath Menon - San Jose CA

International Business Machines Corporation - Armonk NY

G06F 1318

395826

In a data processing system having a plurality of queues for prioritizing I/O requests to a storage device, the priority of the queues for servicing is dynamically adjustable as opposed to each queue having a fixed priority. Dynamically adjusting the priority of a queue allows the priority of a queue with "stuck" requests to be raised so the "stuck" requests can be serviced very quickly.

44634242, Jul 31, 1984

Oct 21, 1983

6/544331

Richard L. Mattson - San Jose CA
Juan A. Rodriguez-Rosell - Gaithersburg MD

International Business Machines Corporation - Armonk NY

G06F 1300

364300

Short traces of consecutive CPU references to storage are accumulated and processed to ascertain hit ratio as a function of cache size. From this determination, an allocation of cache can be made. Because this determination requires minimal processing time, LRU-referenceable memory space among concurrently executing sequential processes is used dynamically by a CPU cache manager.

57348618, Mar 31, 1998

Dec 12, 1995

8/571010

Oded Cohn - Haifa, IL
Richard Lewis Mattson - Pacific Grove CA
Jaishankar Moothedath Menon - San Jose CA

International Business Machines Corporation - Armonk NY

G06F 1212

395461

A log-structured array (LSA) includes a relatively large, non-volatile cache memory as well as a memory segment write buffer. The LSA cache memory contains both updated logical tracks received from the host system and also clean logical tracks read from direct access storage devices of the array. When the fraction of updated tracks in the cache memory exceeds a threshold value, updated tracks are moved from the LSA cache memory to the memory segment. With each modified track to be moved, adjacent modified tracks also are moved. The updated tracks are moved regardless of their location in the updated LRU list. Clean tracks in the LSA cache memory are moved into the memory segment as well, when additional clean tracks are needed in the cache memory. The clean tracks are selected from the bottom of the LSA cache clean track LRU list. Checking for adjacency also can occur at garbage collection time, performed in a background mode.

52650987, Nov 23, 1993

Aug 3, 1990

7/562188

Richard L. Mattson - San Jose CA
Spencer Ng - San Jose CA

International Business Machines Corporation - Armonk NY

G06F 1100

371 111

A method and apparatus are disclosed which minimize the additional read and write loading for each remaining DASD in a DASD array occasioned by a single point of failure where subsets of DASDs may accessed asynchronously (RAID 4 or RAID 5). In this method, parity groups are written across the array in a pattern forming a balanced incomplete block design or the equivalent. In the event of failure of a DASD in the array, then any additional loading resulting from the failure is uniformly spread among the remaining DASDs.

47149965, Dec 22, 1987

Nov 26, 1985

6/801896

Henry M. Gladney - Saratoga CA
Douglas J. Lorch - San Jose CA
Richard L. Mattson - San Jose CA

International Business Machines Corporation - Armonk NY

G06F 900

364300

In a distributed processing system having a source node accessing data objects from a database and a replica node storing replicas of requested source data objects received from the source location, the impact to replicas caused by a change in a source data object is calculated by assigning a version number to the change. An identifier of the portion of the source database affected by the change is generated, as well as a list of replicas containing objects from the affected portion of the database. For a replica location communicating with the source location, a table of the replicas from the list is then recorded along with the version number for communicating to the replica location.