For future reference. There are several resources available that could be used to determine the required configuration.
* Guide to GlassFish High Availability to get an impression of what's required based on the glassfish application server.
* SPECweb2005, SPECjAppServer2004,SPECjAppServer2010 to acquire various benchmarks results
Read
http://www-03.ibm.com/systems/bladecenter/resources/benchmarks/about/#SPECjAppServer2004 for more benchmarks available.