Keeping Compute Nodes seperate from the region server node-- pros and cons

[Ninad Raut]

Hi,
I want to get a design perspective here as to what will be the advantages of
seperating region servers and compute node(to run mapreduce tasks)
Will seperating datanodes from computes node reduce the load on the servers
and avoid swapping problems?
Will this seperation make map reduce tasks less efficient , since we are
doing away with localization issues?
Regards,
Ninad