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From Avinash Lakshman <>
Subject Re: Replicating data over the wan?
Date Wed, 31 Mar 2010 02:05:16 GMT
How far apart are the data centers? Technically there will be an increase in
latency for the writes if you are waiting for acks from the replicas. How
long does it for simple pings between machines in these data centers? If
inconsistency is not an issue you can mitigate this by doing asynchronous
replication by waiting for a successful  response from just one of the
replicas. Apart from that I can't think of anything that is fundamentally an
impediment. We replicate across east and west coast and typically a ping
takes 75 ms.

On Tue, Mar 30, 2010 at 5:49 PM, Erik Holstad <> wrote:

> Is anyone using datacenter aware replication where the replication takes
> place over the wan
> and not over super fast optical cable between the centers?
> Tried to look at all posts related to the topic but haven't really found
> too much, only some things
> about not doing that if using ZooKeeper and some other small comments.
> What are the limitations for this kind of replication, what happens when
> the writes are coming
> in too fast for the replication to be done, assuming some kind of write
> buffer for the replication?
> Not really worried too much about the inconsistent state of the cluster,
> just how well it would
> work is this kind of environment.
> --
> Regards Erik

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