[rabbitmq-discuss] Clustering RabbitMQ between Datacentres

[Simon MacMullen]

On 31/10/11 13:20, Pete Kelly wrote:
> We are looking at clustering our RabbitMQ setup at the moment - however
> we are looking to do it across 2 data centres, one in Europe and one in
> the USA. There is a VPN between the 2 DC's so packets can be routed
> between the 2 networks directly over the VPN.
>
> Is this a good idea, or would it be classed as one of the "WAN"
> scenarios which is warned against in the Clustering guide?

No and yes, unfortunately.

> If it's is a good idea, great! However if not, we will look into having
> clusters at each end with mod shovel or take another approach.

Another approach would be the federation plugin.

> Are there any further docs or explanations anyone can point me to to
> describe the specific problems RabbitMQ has over a "WAN" ?

It's discussed a bit in this blog post:

http://www.rabbitmq.com/blog/2011/06/22/federation-plugin-preview-release/

but the short version is that its the CAP theorem. RabbitMQ clustering 
chooses Consistency and Availability and thus loses Partition Tolerance 
- which doesn't work out so well if the links between nodes can go down.

Cheers, Simon

-- 
Simon MacMullen
RabbitMQ, VMware