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db2top: Buffer pool hit ratio (video)
Today’s video is a demonstration of buffer pool hit ratio in the Bufferpools screen of db2top. To produce a hit ratio of 100%, we query a single row repeatedly to perform logical reads with no corresponding physical reads. To reduce the hit ratio, we query more data than can fit in the buffer pool, resulting [...]
db2top Bufferpools Screen (Part 2)
In the first post on db2top’s Bufferpools screen, we saw aggregates across all of the buffer pools in the database. In this second part, you will see what db2top reports for individual buffer pools. For example, db2top reports: Individual hit ratios The sizes of each buffer pool Asynchronous reads and writes due to prefetchers and [...]
db2top Bufferpools Screen (Part 1)
Considering the dramatic differences in speed between memory access and disk access, it is not surprising that DB2′s own documentation claims that configuring buffer pools is the single most important tuning area for DB2. In most cases, using more than one buffer pool on your system can have performance advantages. For example: Breaking out temporary [...]
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