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From "B. Todd Burruss" <bburr...@real.com>
Subject Re: RackAwareStrategy - add the third datacenter to live cluster with replication factor 3
Date Thu, 11 Feb 2010 21:29:05 GMT
when using rack aware, RF=3, W=QUORUM ... does a write block until
response from both data centers?  and if so is there a setting to make
the write to the "second" data center async?


On Thu, 2010-02-11 at 12:12 -0800, Jonathan Ellis wrote:
> On Thu, Feb 11, 2010 at 1:53 PM, Weijun Li <weijunli@gmail.com> 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 rack.properties 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.
> 
> -Jonathan



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