May i know that what is the different ? 1. java -Xmx22G -Xms22G -XX:+AggressiveOpts -jar craftbukkit.jar after start up the task manager will show that 22G ram is used. 2. java -Xmx22G -Xms1G -XX:+AggressiveOpts -jar craftbukkit.jar after start up the task manager will show that 1G ram is used.