Quite often we need to perform a so-called "MySQL instance audit". This common DBA procedure should give you a general view of the MySQL environment. You may be interested in a basic understanding of what kind of operation MySQL performs, how much memory does it use, or how well does it look from the performance point of view. There is no easy out-of-the-box way to do such an audit on a MySQL server. You can use "SHOW STATUS" and check the list of system variables, but this way can hardly be called DBA-friendly. Fortunately there are several tools to make this process easier. Among most popular are mysqlreport and MySQLTuner. In this post I'd like to give a brief overview of MySQLTuner.So, what can MySQLTuner do? Quoting the documentation: "MySQLTuner is a script written in Perl that will assist you with your MySQL configuration and make recommendations for increased performance and stability. Within seconds, it will display statistics about your MySQL installation and the areas where it can be improved."It's not magic --- they don't use any "hidden" or unknown MySQL features to provide the report. What they do is use "SHOW STATUS" metrics and provide a user-friendly report, interpreting data this or that way. What makes such tools really valuable is the way they interpret that data.