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