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From Allen Wittenauer ...@yahoo-inc.com>
Subject Re: NameNode memory usage and 32 vs. 64 bit JVMs
Date Fri, 07 Nov 2008 06:49:55 GMT



On 11/6/08 10:17 PM, "C G" <parallelguy@yahoo.com> wrote:

> I've got a grid which has been up and running for some time. It's been using a
> 32 bit JVM.  I am hitting the wall on memory within NameNode and need to
> specify max heap size > 4G.  Is it possible to switch seemlessly from 32bit
> JVM to 64bit?  I've tried this on a small test grid and had no issues, but I
> want to make sure it's OK to proceed.

    It should be.  We run name node with 64-bit JVM and everything else with
32-bit.

> Speaking of NameNode, what does it keep in memory?  Our memory usage ramped up
> rather suddenly recently.

    Some one/thing created a ton of files, likely small.  Check your file
system contents, use the fs count command, etc, to look for anomalies.

> Also, does SecondaryNameNode require the same
> amount of memory as NameNode?

    We're actually starting to see that it requires a tad bit more.


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