some further info:
i unpacked the 3.2.2 tar gz added -verbosegc to JAVA_OPTS in run.sh and ran it clean.
System.gc() is called every minute.
I downloaded the 3.2.2 source tarball, cant find any code that calls System.gc, Runtime.getRuntime().gc()
Whats going on ? When I use a large heap ie >2Gb, the Full GC is taking up to 20 secs every minute
Yes, this is an option on your JVM. For Sun VM its -XX:DisableExplicitGC
The RMI subsystem amongst other things is attempting to do full GC in very short intervals.