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Message Posted: Tue, 04 Nov 2003 @ 17:19:14 GMT

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I find the answer different from system-to-system. Also the storage vendor seems to play a part in bettering the ratio.

The best answer I can offer is that the determination of a "good ratio" is one that yields good system workload qualities. Conversely the "bad ratios" are the ones that give impaired system workload.

What I call good numbers range from 100:1 to 2500:1 and beyond. ARCMain distorts those numbers as it is very aggressive on LIO and conservative on CPU. Clearly when I see numbers of 10:1 I am concerned for the quality of the query being submitted. The ratio of 200:1 becomes suspicious. Still the measure I use is the impact the 100:1 query has on canary queries.

Low and high numbers seem to concern me less than the value of having the "Higa Ratio" to easily catch poorly constructed queries. In my opinion the "Higa Ratio" is a ratio formed by trial, error and observation. The number of 1000:1 is a good midpoint and lower than that number alone does not identify a problem query.

Best Regards,

Jim LeBlanc

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