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From Jonathan Ellis <>
Subject Re: RackAwareStrategy - add the third datacenter to live cluster with replication factor 3
Date Thu, 11 Feb 2010 20:12:39 GMT
On Thu, Feb 11, 2010 at 1:53 PM, Weijun Li <> wrote:
> Hello,
> I have a testing cluster with: A (dc1), B (dc1), C(dc2), D(dc2). The
> replication factor is 2 so I assume each DC will have a complete copy of the
> data. Also I'm using PropertyFileEndPointSnitch with for the
> dc and rack settings.
> So, what's the steps to add another datacenter and increase replication
> factor to 3 to ensure that dc3 will also get a complete copy of the data?

RackAwareStrategy only cares about replicating to 2 datacenters out of Y.  So

(1) Write a ReplicationStrategy that extends RAS's algorithm to
replicating to Y of Y DCs
   (1a) alternatively, make RAS configurable to be X of Y where X
could be 2 (current) or Y (your case) or anything in between
(2) deploy the new RS, bring up nodes in your 3rd DC, and repair them.


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