> servers). RS heap is 8G and DN is 12G. I haven't done much testing changing the DN heap, but in my experience it's not really of use to have 12GB there since the data never goes through the DN. Max 2GB maybe, give the rest to the region server or even the OS cache (ie don't allocate some GBs on purpose).
>From what I see in your other responses, it appears that most of your performance testing was done in a black box fashion. Did you try even try looking into where the bottle neck is? If not, then how could we even be able to tell you why 3 RS would be faster than 6 apart from doing educated guesses? As far as I can tell, you might want to see if some region server is serving most of the load or not. If it is, is it because of poor region balancing (all the hottest regions at the same place) or because of poor key design (all the reads hit only one region). That's just one thing to look at. J-D
