Are there any guidelines for estimating the CPU/memory/bandwidth overhead for RHQ server and agents ?
If say I am using the default settings for RHQ storage/server/agent for monitoring a EAP6 server, how much CPU/bandwidth will be required on the agent/server ?
For the log event source for the EAP6 server log, will there be a 1-1 mapping from the log size to the storage required in RHQ storage/Cassandra (1 MB log = 1 MB storage) ?
For RHQ, the limiting factor is I/O, not memory or CPU. Depending on your deployment, it may be Oracle or Cassandra that limits you. Bandwidth use is actually pretty small in my experience.
My advice would be to run the performance plugin on a number of hosts and see what capacity issues you run into.