Configuring and Tuning Databases on the Solaris™ Platform

Monitoring the Buffer Cache

Given that the buffer cache has a significant impact on the performance of OLTP applications, it should be no surprise that monitoring the effectiveness of the buffer cache is an important priority. The buffer cache hit rate is one of the main database metrics that you should monitor for OLTP workloads. The cache hit rate measures how many database blocks were found in the buffer cache rather than read from disk. Blocks read from disk are referred to as physical reads. Blocks retrieved either from disk or the buffer cache are referred to as logical reads (so physical disk reads are included in both metrics). The buffer cache hit rate is calculated in the following way:

BufferCacheHitRate = <1 – (PhysicalReads) / ( ...