Aaron That could be the issue, my data is just 516MB - wouldn't this see a bit of speed up? Could you guide me to the example? I ll run my cluster on it and see what I get. Also for my program I had a java timer running to record the time taken to complete execution. Does Hadoop have an inbuilt timer?
Mithila On Mon, Apr 13, 2009 at 1:13 AM, Aaron Kimball <[email protected]> wrote: > Virtually none of the examples that ship with Hadoop are designed to > showcase its speed. Hadoop's speedup comes from its ability to process very > large volumes of data (starting around, say, tens of GB per job, and going > up in orders of magnitude from there). So if you are timing the pi > calculator (or something like that), its results won't necessarily be very > consistent. If a job doesn't have enough fragments of data to allocate one > per each node, some of the nodes will also just go unused. > > The best example for you to run is to use randomwriter to fill up your > cluster with several GB of random data and then run the sort program. If > that doesn't scale up performance from 3 nodes to 15, then you've > definitely > got something strange going on. > > - Aaron > > > On Sun, Apr 12, 2009 at 8:39 AM, Mithila Nagendra <[email protected]> > wrote: > > > Hey all > > I recently setup a three node hadoop cluster and ran an examples on it. > It > > was pretty fast, and all the three nodes were being used (I checked the > log > > files to make sure that the slaves are utilized). > > > > Now I ve setup another cluster consisting of 15 nodes. I ran the same > > example, but instead of speeding up, the map-reduce task seems to take > > forever! The slaves are not being used for some reason. This second > cluster > > has a lower, per node processing power, but should that make any > > difference? > > How can I ensure that the data is being mapped to all the nodes? > Presently, > > the only node that seems to be doing all the work is the Master node. > > > > Does 15 nodes in a cluster increase the network cost? What can I do to > > setup > > the cluster to function more efficiently? > > > > Thanks! > > Mithila Nagendra > > Arizona State University > > >
