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From Robert Coli <rc...@eventbrite.com>
Subject Re: Is nodetool cleanup necessary on nodes of different data center when new node is added
Date Thu, 07 Aug 2014 22:08:03 GMT
On Thu, Aug 7, 2014 at 2:46 PM, Viswanathan Ramachandran <
vish.ramachandran@gmail.com> wrote:

> I plan to have a multi data center Cassandra 2 setup with 2-4 nodes per
> data center and several 10s of data centers. We have My understanding is
> that nodetool cleanup removes data which no longer belongs to that node.
> When a new data center is being setup, we are creating completely new
> replicas and AFAICT, it does not result in data movement/rebalance outside
> of this new data center and hence there is no cleanup requirement on nodes
> of other data centers. Is someone able to confirm if my understanding is
> right, and cleanup is not required on nodes of other data centers?
>
This is the correct understanding; as you say, the key is that cleanup
removes data which no longer belongs to a node. In this situation, no node
loses responsibility for any replica, so cleanup is not necessary.

For what it's worth, 2-4 nodes per data center and several 10s of data
centers is an unusual deploy for Cassandra. If you can discuss it, what is
the use case?

=Rob

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