Understanding Buffer Pool Performance and ... - Quest Software

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Evaluating <strong>Performance</strong> Metrics VCR Victim Cleans Ratio You Can Expect More ⎛ ⎞ ⎜ ⎟ ⎜ dirty. page. steal. cleaner. triggers ⎟ = ⎜ * 100 ⎛ dirt. page. steal. cleaner. triggers + lsn. gap. cleaner. triggers ⎞ ⎟ ⎜ ⎟ ⎜ ⎜ ⎟ . . . . ⎟ ⎝ ⎝ + dirty page threshold cleaner triggers ⎠ ⎠ – Above 40%, typically means buffer pool needs to be larger – Could also mean SOFTMAX parameter is too high (not enough page turnover) – 0 if ALTERNATE_PAGE_CLEANING=ON
Conclusion You Can Expect More • Focus on three main areas 1. BP hit ratios (logical vs. physical) 2. Prefetcher tuning (asynchronous vs. synchronous) 3. Page cleaner tuning (if not using newer alternate cleaning) • Collect performance data over time – Sampling methodology – snapshots every 5-15 minutes over the course of the day, or during a batch run • Review the results – Decipher data <strong>and</strong> plug into equations – Know the workload – Chart performance over time • Take action – Various solutions depending on findings
Page 1 and 2: Understanding Buffer Pool Performan
Page 3 and 4: Introduction You Can Expect More Q:
Page 5 and 6: Buffer Pool Overview Basics and Ter
Page 7 and 8: Buffer Pool Overview Tuning Goals
Page 9 and 10: Buffer Pool Overview Prefetch You C
Page 11 and 12: You Are Here - DB2 Process Model Li
Page 13 and 14: Buffer Pool Management You Can Expe
Page 19 and 20: Collecting Performance Metrics Tuni
Page 21 and 22: Collecting Performance Metrics DB2
Page 23 and 24: Collecting Performance Metrics •
Page 25 and 26: Collecting Performance Metrics •
Page 27 and 28: Evaluating Performance Metrics You
Page 29 and 30: Evaluating Performance Metrics Data
Page 31 and 32: Evaluating Performance Metrics Phys
Page 33 and 34: Evaluating Performance Metrics Pref
Page 35 and 36: Evaluating Performance Metrics Eval
Page 37: Evaluating Performance Metrics TCR

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