version is rewally important here.. - If 1.x, then Where (NN , JT , TT ?) - if 2.x, then where? (AM, NM, ... ?) <-- probably less likely here, since the resources are ephemeral.
I know that some older 1x versions had an issue with the jobtracker having an ever-expanding hashmap or something like that, so that if you ran 100s of jobs, you could get OOM erros on the JobTracker.
