Before you proceed with JavaTM Virtual Machine tuning, it is important to note the following:
| • | Foglight® 5 is a Java application that ships with and uses the Oracle® Java Hotspot Virtual Machine (JVM). While there are other vendors of JVMs, the Oracle JVM should not be replaced or altered. | 
This section provides information on how to tune the JVM to achieve maximum performance.
The following factors heavily impact JVM utilization:
| • | the length of the time period for which Foglight® is configured to preserve historical data about observations  | 
| • | 
To review or modify Foglight® JVM configuration options, locate the following file:
Foglight reads JVM options from values of server.vm.optionsX properties, where X is a number from 0 to 99.
| The JVM options currently in effect (the default Foglight JVM options, server.config settings, and command line arguments) are all logged in the server log file during startup. | 
The following table describes the most commonly used Oracle® Hotspot JVM options: