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From anand_s <>
Subject Re: Question on load balancing in a cluster
Date Mon, 09 Aug 2010 17:09:11 GMT

Cool thanks, I think I will experiment with nodetool move.

Can somebody confirm on the reason for decommissioning, instead of just
splitting the token on the fly? Yes it does seem simpler to just
decommission and bootstrap, but that does mean a lot of data has to be moved
around to get a reasonable load distribution. Load distribution is a bigger
need when a new node is introduced and so load needs to be balanced.  This
also means that when a node is decommissioned the load on its immediate
neighbor increases. 

In this example where A,B,C,E is a cluster with load being 80, 78, 83, 84.
ow I add a new node D (position will be before E), so eventually after all
the rebalance activity I want the load to be ~66 (245/5). Now is that
unreasonable to expect, because if it is not then the each node will have to
be decommissioned and bootstrapped to get that distribution (almost the
entire dataset will need to be moved), now that is a lot of data movement!!
unless I have got this wrong?
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