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From Doug Cutting <cutt...@apache.org>
Subject Re: Scaling hadoop up
Date Thu, 29 Mar 2007 20:37:44 GMT
Michael Bieniosek wrote:
> When I try to scale Hadoop up to about 100 nodes on EC2 (single-cpu Xen), I
> notice things start to fall apart.  For example, the jobtracker starts
> dropping requests with the message "Call queue overflow discarding oldest
> call".  I've also seen problems with the namenode where dfs requests fail
> with EOFExceptions.

What version of Hadoop are you seeing this with?  Scalability has been 
improving.

> I've tried increasing the heartbeat value for the dfs (it's not configurable
> for the jobtracker though).  Is there some other trick to make hadoop scale
> a little further?  The website claims that Hadoop has scaled to 600 nodes,
> but it seems like I would need a very powerful machine for the namenode and
> jobtracker to do this.  Am I missing something?

Yahoo! does use dual-processor nodes that are more powerful than EC2's 
virtual nodes, but probably not 6x more powerful.

Doug

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