Richard L Mattson

US Patent:

59372052, Aug 10, 1999

Filed:

Dec 6, 1995

Appl. No.:

8/568327

Inventors:

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

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1318

US Classification:

395826

Abstract:

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.

US Patent:

57348618, Mar 31, 1998

Filed:

Dec 12, 1995

Appl. No.:

8/571010

Inventors:

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

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1212

US Classification:

395461

Abstract:

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.

US Patent:

55510035, Aug 27, 1996

Filed:

Feb 14, 1994

Appl. No.:

8/196047

Inventors:

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

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1324

US Classification:

395463

Abstract:

Seek affinity is preserved in a segment oriented, cached, log structured array (LSA) of DASDs responsive to accesses dominated by sequential read and random writes of logical tracks stored in the segments. This is achieved by collecting all the write modified read active tracks and clean read active tracks either destaged from the cache or garbage collected from the LSA and rewriting them out to the LSA as segments into regions of contiguous segments of read active tracks. Also, all write modified read inactive tracks and clean read inactive tracks either destaged from cache or garbage collected from the LSA are collected and rewritten out to the LSA as segments into regions of contiguous segments of read inactive tracks. Garbage collection is initiated when the detected free space in a region falls below a threshold and continues until the collected segments exceed a second threshold. Alternatively, write age of logical tracks may be used instead of read activity so as to cluster LSA DASDs into a region of segments formed from old write active logical tracks and a region of current write active logical tracks.