Spotlight on DB2 6.10 - User Guide

Data Read Rate graph

The Data Read Rate graph depicts rates for retrieving data pages from the selected buffer pool over consecutive monitoring intervals. These rates are based on the number of pages read per second. The graph contains the following series:

• Logical —Plots the rate of read requests for data pages that are already in the buffer pool.

• Physical —Plots the rate at which logical read requests required actual database I/O to get the data pages into the buffer pool first. When the physical read rate is consistently higher than the logical read rate, the buffer pool is not being used effectively.

• Synch —Plots the rate of synchronous data reads. When synchronous reads are used to retrieve data pages from the database to put them into the buffer pool, further execution of the query is blocked until these reads are completed. A high synchronous read rate can degrade performance.

For related statistical information

The Statistics tab shows the buffer pool read counts used to generate this graph. The names for these statistics begin with Buffer Pool. These statistics are derived from the POOL data elements that the DB2 snapshot monitor captures.