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US007680982B2
(12) United States Patent ao) Patent No.: Us 7,680,982 B2
Ash et al. (45) Date of Patent: Mar. 16,2010
(73) Assignee: International Business Machines Corporation, Armonk, NY (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 454 days.
(21) Appl.No.: 11/676,634
(22) Filed: Feb. 20, 2007
(65) Prior Publication Data
US 2008/0201523 Al Aug. 21, 2008
(51) Int. CI.
G06F12/00 (2006.01)
(52) U.S. CI 711/113; 711/154; 711/158;
711/162; 711/165; 707/204; 714/5; 714/6
(58) Field of Classification Search 711/113,
711/154, 158, 162, 165; 707/204; 714/5,
714/6
See application file for complete search history. (56) References Cited
U.S. PATENT DOCUMENTS 4,916,605 A * 4/1990 Beardsley et al 711/162
In a data storage subsystem with disk storage and a pair of clusters, one set of DASD fast write data is in cache of one cluster and in non-volatile data storage of the other. In response to a failover of one of the pair of clusters to a local cluster, the local cluster converts the DASD fast write data in local cache to converted fast write data to prioritize the converted data for destaging to disk storage. In response to failure to destage, the local cluster allocates local non-volatile storage tracks and emulates a host adapter to store the converted fast write data by the local non-volatile storage, reconverting the converted fast write data of the non-volatile storage to local DASD fast write data stored in the local non-volatile storage and stored in the local cache storage.
30 Claims, 6 Drawing Sheets
