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From Mithila Nagendra <mnage...@asu.edu>
Subject Re: Map-Reduce Slow Down
Date Tue, 14 Apr 2009 01:28:09 GMT
Yes I can..

On Mon, Apr 13, 2009 at 5:12 PM, Jim Twensky <jim.twensky@gmail.com> wrote:

> Can you ssh between the nodes?
>
> -jim
>
> On Mon, Apr 13, 2009 at 6:49 PM, Mithila Nagendra <mnagendr@asu.edu>
> wrote:
>
> > Thanks Aaron.
> > Jim: The three clusters I setup had ubuntu running on them and the dfs
> was
> > accessed at port 54310. The new cluster which I ve setup has Red Hat
> Linux
> > release 7.2 (Enigma)running on it. Now when I try to access the dfs from
> > one
> > of the slaves i get the following response: dfs cannot be accessed. When
> I
> > access the DFS throught the master there s no problem. So I feel there a
> > problem with the port. Any ideas? I did check the list of slaves, it
> looks
> > fine to me.
> >
> > Mithila
> >
> >
> >
> >
> > On Mon, Apr 13, 2009 at 2:58 PM, Jim Twensky <jim.twensky@gmail.com>
> > wrote:
> >
> > > Mithila,
> > >
> > > You said all the slaves were being utilized in the 3 node cluster.
> Which
> > > application did you run to test that and what was your input size? If
> you
> > > tried the word count application on a 516 MB input file on both cluster
> > > setups, than some of your nodes in the 15 node cluster may not be
> running
> > > at
> > > all. Generally, one map job is assigned to each input split and if you
> > are
> > > running your cluster with the defaults, the splits are 64 MB each. I
> got
> > > confused when you said the Namenode seemed to do all the work. Can you
> > > check
> > > conf/slaves and make sure you put the names of all task trackers there?
> I
> > > also suggest comparing both clusters with a larger input size, say at
> > least
> > > 5 GB, to really see a difference.
> > >
> > > Jim
> > >
> > > On Mon, Apr 13, 2009 at 4:17 PM, Aaron Kimball <aaron@cloudera.com>
> > wrote:
> > >
> > > > in hadoop-*-examples.jar, use "randomwriter" to generate the data and
> > > > "sort"
> > > > to sort it.
> > > > - Aaron
> > > >
> > > > On Sun, Apr 12, 2009 at 9:33 PM, Pankil Doshi <forpankil@gmail.com>
> > > wrote:
> > > >
> > > > > Your data is too small I guess for 15 clusters ..So it might be
> > > overhead
> > > > > time of these clusters making your total MR jobs more time
> consuming.
> > > > > I guess you will have to try with larger set of data..
> > > > >
> > > > > Pankil
> > > > > On Sun, Apr 12, 2009 at 6:54 PM, Mithila Nagendra <
> mnagendr@asu.edu>
> > > > > wrote:
> > > > >
> > > > > > 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 <
> aaron@cloudera.com
> > >
> > > > > 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 <
> > > mnagendr@asu.edu>
> > > > > > > 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
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

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