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From Daniel Doubleday <>
Subject Re: Best Practice for Data Center Migration
Date Fri, 03 Dec 2010 10:37:32 GMT
Hm - 

assuming that you have configured your initial tokens in a way that every next start token
lives in the other datacenter wouldn't it suffice to decrease rf to 2 switch to simple replication
strategy switch off the old dc and start repairs/cleanup?

every row should live in either primary node or the node after the the primary (when the primary
was located in the switched off dc)

Daniel Doubleday, Berlin

On Dec 2, 2010, at 6:11 PM, Jonathan Ellis wrote:

> On Thu, Dec 2, 2010 at 4:08 AM, Jake Maizel <> wrote:
>> Hello,
>> We have a ring of 12 nodes with 6 in one data center and 6 in another.
>>  We want to shutdown all 6 nodes in data center 1 in order to close
>> it down.  We are using a replication factor of 3 and are using
>> RackAwareStrategy with version 0.6.6.
>> We have been thinking that using decomission on each of the nodes in
>> the old data center one at a time would do the trick.  Does this sound
>> reasonable?
> That is the simplest approach.  The major downside is that
> RackAwareStrategy guarantees you will have at least one copy of _each_
> row in both DCs, so when you are down to 1 node in dc1 it will have a
> copy of all the data.  If you have a small enough data volume to make
> this feasible then that is the option I would go with.
>> We have also been considering increasing the replication factor to 4
>> and then just shutting down all the old nodes.  Would that work as far
>> as data availability would go?
> Not sure what you are thinking of there, but probably not. :)
> -- 
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of Riptano, the source for professional Cassandra support

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