Additional Hit Ratios to Track.....

VP Hit Ratio(Getpages - HP Reads - Synch Reads - Asynch Reads)/Getpages
HP Hit Ratio - First Way HP Reads/Getpages
- % of Pages found in HP
HP Hit Ratio - Second WayHP Reads/(Getpages - Synch Reads - Asynch Reads)
- % of BP Hits found in HP
HP Effectiveness Ratio Pages Read from HP / Pages Written to HP
- 1% or 2% is not Good..... 10+% might be....

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Notes:

We also want to track several different types of hit ratios when HiperPools are in use. This gives us the ability to measure the efficiency of each pool resource. Even considering that the movement of a page from a HP to a VP is only 35 Mcs, it is still more efficient to find the page in the VP.

While small HP re-use percentages may seem to provide little benefit, these percentages must still be evaluated compared to the overall i/o rate per second to determine whether the HP is wasted, or is providing a reasonable performance improvement.

While backing the sort/work pool with a HP often provides no benefit, there have been several installations that did obtain significant performance benefits from this approach. So, as usual, it depends.....