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From Jeremy Hanna <jeremy.hanna1...@gmail.com>
Subject Re: 4/20 nodes get disproportionate amount of mutations
Date Tue, 23 Aug 2011 07:52:02 GMT

On Aug 23, 2011, at 2:25 AM, Peter Schuller wrote:

>> We've been having issues where as soon as we start doing heavy writes (via hadoop)
recently, it really hammers 4 nodes out of 20.  We're using random partitioner and we've set
the initial tokens for our 20 nodes according to the general spacing formula, except for a
few token offsets as we've replaced dead nodes.
> 
> Is the hadoop job iterating over keys in the cluster in token order
> perhaps, and you're generating writes to those keys? That would
> explain a "moving hotspot" along the cluster.

Yes - we're iterating over all the keys of particular column families, doing joins using pig
as we enrich and perform measure calculations.  When we write, we're usually writing out for
a certain small subset of keys which shouldn't have hotspots with RandomPartitioner afaict.

> 
> -- 
> / Peter Schuller (@scode on twitter)


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