The Present.....

Updated Pages

Locked

Queue Per DS

Pages In-Use

Being Read Into

Available

Synchronous LRU Queue

Prefetch LRU Queue

VWTH

10%

DWTH

50%

IWTH

97.5%

DMTH

95%

SPTH

90%

VPSEQT

80%

VPPSEQT % of VPSEQT for Parallel Sequential... default 50%

Note >>>

Free

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Notes:

The pages in the left two sections of the pool illustration are the ‘CBA’ pages. DB2s usage of the two basic LRU queues is critical to overall pool performance. Now that the percentages of the pages used for each queue is adjustable, we have precise tuning ability. The ‘Free’ page queue is maintained only if Hiperpools are in use, and can be used for pages being moved back from a hiperpool, or new pages being read into the pool from external storage. In either case, it is more efficient since pages will not have to be freed or stolen from the other two queues, or migrated to a HP to make room for the new pages. The VPPSEQT default threshold is 40% of whatever value the VPSEQT has...so if the pool has 10,000 buffers, and the VPSEQT is 80%, then the default 40% VPSEQT provides 3200 buffers. If Parallel I/O is not being used, the VPPSEQT does not matter...if you want to disable it, set VPPSEQT to 0%.