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From Harsh J <qwertyman...@gmail.com>
Subject Re: Question on Master
Date Wed, 16 Mar 2011 17:43:05 GMT
NameNode and JobTracker do not require a lot of storage space by
themselves. The NameNode needs some space to store its edits and
fsimage, and both require logging space.

However, you may make use of multiple disks for NameNode, in order to
have a redundant backup copy of the NN image available in case one of
the disks crash. Other solutions to this second/third location include
storing to an HA-NFS mount, or an externally attached disk mount.

NameNode data is stored in the ${dfs.name.dir} set of directories
[Defined in hdfs-site.xml]. Ensure its content is preserved perfectly
(including permissions) if you're planning to switch disks for your

On Wed, Mar 16, 2011 at 10:04 PM, Mark <static.void.dev@gmail.com> wrote:
> I know the master node is responsible for namenode and job tracker, but
> other than that is there any data stored on that machine? Basically what I
> am asking is should there be an generous amount of free space on that
> machine?
> So for example I have a large drive I want to swap out of my master and put
> into another machine which will be a used as a node. Before doing this, is
> there anything I should back up from my master? Where is the namenode data
> stored?
> Thanks

Harsh J

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