SQL Server Tips by Robin Schumacher

What is Ratio Analysis?

Ratio-based analysis has been around for many years. It used to be the only technique database administrators employed when called upon to diagnose the cause of database slowdown. Using one or more cherished SQL scripts; the DBA would conduct an examination of key ratios such as database memory use, contention, I/O, network utilization, and others to pinpoint the area(s) responsible for unacceptable performance.

Once a particular area was identified as suspect, the standard remedy was to increase the resources for that area. This often did the trick but occasionally failed to produce any real performance gain.

Should ratio-based analysis still be used to assist in determining the overall health of a database, and if so, how should it be done?

When performed correctly, ratio-based analysis definitely has a place in the DBA’s performance-tuning arsenal. Performance ratios are very good roll-up mechanisms for busy DBAs, making at-a-glance analysis possible.

Many DBAs have large database farms to contend with and cannot spend time checking detailed wait-based analysis outputs for every SQL Server they oversee. Succinct performance ratios can assist in such situations by giving DBAs a few solid indicators that can be scanned quickly to see if any database server requires immediate attention.

The above book excerpt is from:

High-Performance SQL Server DBA
Tuning & Optimization Secrets

ISBN: 0-9761573-6-5
Robin Schumacher

 http://www.rampant-books.com/book_2005_2_sql_server_dba.htm