best way to set memory

[Fernando Padilla]

So.. I want to have different memory profiles for 
NameNode/DataNode/JobTracker/TaskTracker.

But it looks like I only have one environment variable to modify, 
HADOOP_HEAPSIZE, but I might be running more than one on a single 
box/deployment/conf directory.

Is there a proper way to set the memory for each kind of server? Or has 
an issue been created to document this bug/deficiency??