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MapReduce >> mail # user >> HDFS disable balancing cluster

Robin Verlangen 2012-08-17, 09:54
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RE: HDFS disable balancing cluster
In 1.x
The exclude* configuration list will allow you to fine tune which node does processing or storage or both  (Process vs Storage node)

This will work for "dynamic sizing" of process nodes.
It does not work well for "dynamically sizing" your storage nodes. As you have already discovered or known.


P.S. Check your EC2 bill.  You'r gonna be reading a lot of data across with your model
From: Robin Verlangen [mailto:[EMAIL PROTECTED]]
Sent: Friday, August 17, 2012 2:54 AM
Subject: HDFS disable balancing cluster

Hi there,

We currently run an eight node cluster on Amazon EC2. This is perfect for our storage, but we want to add a couple of nodes (lets say 32) for processing a big task. We spin them up, run the jobs, and terminate the machines.

Sounds OK to me, however I'm aware of the fact that hadoop tries to replicate data blocks to other nodes in favor of balancing the cluster. I don't want this, as I will get under-replicated blocks when terminating the machines.

We use juju for easy cluster administration. This implies that adding a new hadoop-slave runs both hdfs and hadoop (mapred).

My main question is, is it possible to disable balancing the cluster, or just to disable the datanode service on the new nodes (meant for processing only)?
Best regards,

Robin Verlangen
Software engineer

W http://www.robinverlangen.nl

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Steve Loughran 2012-08-17, 15:09