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From Aaron Kimball <aa...@cloudera.com>
Subject Re: HDFS is not loading evenly across all nodes.
Date Thu, 18 Jun 2009 20:26:34 GMT
Did you run the dfs put commands from the master node?  If you're inserting
into HDFS from a machine running a DataNode, the local datanode will always
be chosen as one of the three replica targets. For more balanced loading,
you should use an off-cluster machine as the point of origin.

If you experience uneven block distribution, you should also periodically
rebalance your cluster by running bin/start-balancer.sh every so often. It
will work in the background to move blocks from heavily-laden nodes to
underutilized ones.

- Aaron

On Thu, Jun 18, 2009 at 12:57 PM, openresearch <
Qiming.He@openresearchinc.com> wrote:

> Hi all
> I "dfs put" a large dataset onto a 10-node cluster.
> When I observe the Hadoop progress (via web:50070) and each local file
> system (via df -k),
> I notice that my master node is hit 5-10 times harder than others, so hard
> drive is get full quicker than others. Last night load, it actually crash
> when hard drive was full.
> To my understand,  data should wrap around all nodes evenly (in a
> round-robin fashion using 64M as a unit).
> Is it expected behavior of Hadoop? Can anyone suggest a good
> troubleshooting
> way?
> Thanks
> --
> View this message in context:
> http://www.nabble.com/HDFS-is-not-loading-evenly-across-all-nodes.-tp24099585p24099585.html
> Sent from the Hadoop core-user mailing list archive at Nabble.com.

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