It will use more than that. I have just been running some perf tests with a 1GB heap and my JVMs memory usage was over 1GB. But that was not on a VM. Hmm, I have a Server 2008 VM, perhaps I'll fire it up and run my code there - I'll let you know my results. I see the term "JavaService". Are you certain that you changed the JVM parameters properly? JavaService (if it is http://wrapper.tanukisoftware.org/) uses registry entries to specify the heap size. Also, it has been a while since I used JavaService and I cannot remember if it forks a separate Java process or if it loads the JVM DLL directly. A tool such as Process Explorer from sysinternals should shed light on that. Also, if you set the pagefile to 0, make sure you allocate enough memory to the virtual machine. Without the JVM running you should have at least 1.5GB free memory. You might have to allocate 2.5GB or 3GB to the virtual machine. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4227047#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...