Cache queue entry linking for DASD record updates

专利名称：Cache queue entry linking for DASD record

updates

发明人：Susan Kay Candelaria,Vernon John

Legvold,Warren Keith Stanley

申请号：US08/414826申请日：19950331公开号：US05682513A公开日：19971028

摘要：A data storage system provides disaster recovery capability by asynchronouslytransmitting record updates to a secondary site in sequence consistent order. Suchrecord updates are stored at a primary site in a cache memory of a storage controller. Acircular queue is created having a head pointer for locating a first (or oldest) recordupdate with subsequent record updates of a track being linked therefrom in sequenceconsistent order. A tail pointer of the circular queue points to the last record update. Acounter field is provided in a track slot header for counting a number of updated recordsin the track and hence the circular queue. When a data mover in the host processor at theprimary site reads record updates for transmission to the secondary site, the data moverstarts with the record update pointed to by the head pointer such that the data movermoves through the circular queue (and hence the record updates) in a backward chainfashion. The counter is decremented as each record update in the track is read by thedata mover such that when the counter reaches zero the data mover knows that no otherrecord updates exist for that track.

申请人：INTERNATIONAL BUSINESS MACHINES CORPORATION

代理人：F. E. Anderson,R. M. Sullivan

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