Raymond, Load wise, it should be very safe to run both JT and NN on a single node for small clusters (< 40 Task Trackers and/or Data Nodes). They don't use much CPU as such.
This may even work for larger clusters depending on the type of hardware you have and the Hadoop job mix. We usually observe < 5% CPU load with ~80 DNs/TTs on an 8-code Intel processor based box with 16GB RAM. It is best that you observe CPU & mem load on the JT+NN node to take a call on whether to separate them. iostat, top or sar should tell you. Regards, Sriguru >-----Original Message----- >From: John Martyniak [mailto:j...@beforedawnsolutions.com] >Sent: Friday, November 27, 2009 3:06 AM >To: common-user@hadoop.apache.org >Cc: <common-user@hadoop.apache.org> >Subject: Re: Good idea to run NameNode and JobTracker on same machine? > >I have a cluster of 4 machines plus one machine to run nn & jt. I >have heard that 5 or 6 is the magic #. I will see when I add the next >batch of machines. > >And it seems to running fine. > >-Jogn > >On Nov 26, 2009, at 11:38 AM, Yongqiang He <heyongqiang...@gmail.com> >wrote: > >> I think it is definitely not a good idea to combine these two in >> production >> environment. >> >> Thanks >> Yongqiang >> On 11/26/09 6:26 AM, "Raymond Jennings III" <raymondj...@yahoo.com> >> wrote: >> >>> Do people normally combine these two processes onto one machine? >>> Currently I >>> have them on separate machines but I am wondering they use that >>> much CPU >>> processing time and maybe I should combine them and create another >>> DataNode. >>> >>> >>> >>> >>> >> >>
