Patent
1995-06-19
1997-07-15
Chan, Eddie P.
395439, 395440, 395460, 395465, G06F 1202
Patent
active
056491530
ABSTRACT:
A cache management system for dynamically switching between record caching and track caching. Statistics are collected within the cache management system to determine the type and amount of locality associated with a specific data set currently within the cache. Using these statistics, metrics of the actual hit ratio, whole-track hit ratio, and other-record-hit ratio are generated. The metrics are periodically reviewed for a given band, and the band is placed into one of three cache modes accordingly. The mode assignment determines what type of staging will be performed for data within the band in the event of a miss. The possible modes are: track mode for track-based staging, record mode for staging of a single record only, or uncached mode if no data is to be staged. If a band has been assigned to either record or track mode, the assignment is re-evaluated after for a predetermined number of I/O's (128). If the band has been assigned to uncached mode, then after another predetermined number of I/O's (4096), the band is reassigned to record mode in order to force an update of the band statistics.
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Azevedo Ruth Enid
Harding Barrie N.
McNutt Bruce
Morain Gary E.
Chan Eddie P.
International Business Machines - Corporation
Klein Esther E.
Yip Vincent
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