We have Glassfish application server running in Linux servers. Each Glassfish installation hosts 3 domains. Each domain has a JVM configuration such as -Xms 1GB and -XmX 2GB. That means if all these three domains are running at max memory, server should be able to allocate total 6GB to the JVMs

With that math,each of our server has 8GB RAM (2 GB Buffer) First of all - is this a good approach? I did not think so, because when we analyzed memory utilization on this server over past few months, it was only up to 1GB;

Now there are requests to add an additional domain to these servers - does that mean to add additional 2 GB RAM just to be safe or based on trend, continue with whatever memory the server has?