International Business Machines Corporation

Steven Robert Lowe

Thomas Charles Jarvis

Kevin J Ash

Karl Allen Nielsen

Kenneth Wayne Todd

Michael Howard Hartung

David Frank Mannenbach

Jeremy Michael Pinson

Lokesh M Gupta

Alfred Emilio Sanchez

William Dennis Williams

Michael T Benhase

Carol Santich Mellgren

Binny Sher Gill

Brent Cameron Beardsley

Joseph S Hyde, Ii

Bruce McNutt

Sam Clark Werner

Lawrence Carter Blount

Vernon John Legvold

Luis Angel Daniel Bathen

Kevin John Ash

Lokesh Mohan Gupta

Provided are a method, system, and program for destaging a track from cache to a storage device. The destaged track is retained in the cache. Verification is made of whether the storage device successfully completed writing data. Indication is made of destaged tracks eligible for removal from the cache that were destaged before the storage device is verified in response to verifying that the storage device is successfully completing the writing of data.

Demoting tracks from cache

System and program for demoting tracks from cache

Provided are a method, system, and article of manufacture for copying data from a first cluster to a second cluster to reassign storage areas from the first cluster to the second cluster. An operation is initiated to reassign storage areas from a first cluster to a second cluster, wherein the first cluster includes a first cache and a first storage unit and the second cluster includes a second cache and a second storage unit. Data in the first cache for the storage areas to reassign to the second cluster is copied to the second cache. Data in the first storage unit for storage areas remaining assigned to the first cluster is copied to the second storage unit.

Copying data from a first cluster to a second cluster to reassign storage areas from the first cluster to the second cluster

Provided are a method, system, and article of manufacture for adjusting parameters used to prefetch data from storage into cache. Data units are added from a storage to a cache, wherein requested data from the storage is returned from the cache. A degree of prefetch is processed indicating a number of data units to prefetch into the cache. A trigger distance is processed indicating a prefetched trigger data unit in the cache. The number of data units indicated by the degree of prefetch is prefetched in response to processing the trigger data unit. The degree of prefetch and the trigger distance are adjusted based on a rate at which data units are accessed from the cache.

Adjusting parameters used to prefetch data from storage into cache

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.

Preservation of cache data following failover

Method for demoting tracks from cache

An apparatus and a method to allocate device adapter bandwidth, where that device adapter is disposed in an information storage and retrieval system capable of communicating with one or more host computers, and where that device adapter interconnects a data cache with information storage devices. The data storage and retrieval system receives a plurality of requests from the host computers to read information from, or to write information to, information storage devices. The method determines a read/write request ratio and a non-volatile storage utilization ratio. The method allocates device adapter bandwidth based upon the read/write request ratio and/or the non-volatile storage utilization ratio.

Apparatus and method to dynamically allocate bandwidth in a data storage and retrieval system

A data storage control unit is coupled to one or more host devices and to one or more physical storage units, the physical storage units collectives configured as a plurality of logical storage ranks. The storage control unit receives and processes write requests from the host devices and directs that data updates be stored in a temporary storage. The data updates are subsequently destaged to the logical ranks. Write requests are processed at a predetermined rate relative to the rate at which destages are performed (destage mode or rate). The storage control unit evaluates workload conditions of the temporary storage and modifies the destage mode if the temporary storage is in danger of becoming backlogged or if an actual backlog is created, thereby applying a 'throttle' to the host write requests. Thus, method, apparatus and program product are provided to dynamically modify a level of throttling whereby through-put of a host device is substantially maintained.

Increasing through-put of a storage controller by autonomically adjusting host delay

Provided are a method, system, and program for maintaining data in a first cache and second cache, wherein a backup cache maintains a backup copy of data in the first cache, and wherein the first cache is used to cache a first set of data in a storage system and the second cache is used to cache a second set of data in the storage system. An unavailable state of the first cache is detected. In response to detecting the unavailable state, requests to the first set of data are blocked and at least one space in the second cache is allocated for data in the backup cache. Requests to the first set of data are allowed to proceed after the at least one space is allocated in the second cache and before the data in the backup cache is copied to the at least one allocated space in the second cache. The data from the backup cache is copied to the allocated at least one space in the second cache after the requests to the first set of data are allowed to proceed.

Method, system, and program for restoring data in cache

Provided are a method, system, and program for increasing processor utilization. A list of work is divided for processing among a plurality of processes, wherein a process is allocated a part of the list of work to process, and the processes execute in parallel. If a process completes the list of work allocated to the process then the process is made available on an available process queue. Before a process performs any work, the process reads the available process queue and determines if any process is available to share the work. If so, the work is split up between the examining process and the available process. In one implementation, the work involves scanning a cache and if necessary destage data.

Method, system, and article of manufacture for increasing processor utilization

Provided is a method, system, and program for destaging data from a first computer readable medium to a second computer readable medium. A list of entries indicating data blocks in the first computer readable medium is scanned. For each entry scanned, a determination is made as to whether the data block indicated in the scanned entry satisfies a criteria. If the data block indicated in the scanned entry satisfies the criteria, then a destage operation is called to destage the data block in the scanned entry from the first computer readable medium to the second computer readable medium. If the called destage operation is not initiated, then the scanned entry is removed from the cache list. The removed scanned entry is added to one destage wait list. During one destage operation, data blocks indicated in entries in the destage wait list are destaged.

Method, system, and program for destaging data in cache

In a cache management system multiple cache lists are utilized, where each entry in a list names at least one corresponding data item in cache. A cache manager always demotes cache list entries from a &ldquo;current removal list&rdquo; (and demotes or destages the corresponding data items from cache) until that list is exhausted and another list rotates into the function of current removal list. A prescribed order is established for rotating the role of current removal list. In response to prescribed activities of data items in cache, new cache list entries are added nearer or farther from the current removal list according to the prescribed order and the data items' priorities.

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Tucson, AZ, United States of America

Steven Robert Lowe