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From Rob Coli <>
Subject Re: Changing replication factor from 2 to 3
Date Wed, 02 Jun 2010 21:12:31 GMT
On 6/2/10 12:49 PM, Eric Halpern wrote:
> We'd like to double our cluster size from 4 to 8 and increase our replication
> factor from 2 to 3.
> Is there any special procedure we need to follow to increase replication?
> Is it sufficient to just start the new nodes with the replication factor of
> 3 and then reconfigure the existing nodes to the replication factor one at a
> time?
Replication factor is not really intended to be changed in a live 
cluster either, but increasing it may be done if you (a) use 
ConsistencyLevel.QUORUM or ALL (depending on your existing replication 
factor) to make sure that a replica that actually has the data is 
consulted, (b) are willing to accept downtime while anti-entropy repair 
runs (see below), or (c) are willing to live with some clients 
potentially being told no data exists if they read from the new replica 
location(s) until repair is done.

Please feel free to update this wiki page if the above information is 
incomplete in any way. :)


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