[rabbitmq-discuss] MCollective using a RabbitMQ Cluster

Simon MacMullen simon at rabbitmq.com
Wed Nov 9 14:38:50 GMT 2011

On 09/11/11 02:27, Jon Jon wrote:
> Hello All,
> I'm looking to implement an MCollective platform in my data center.


> I would like to use a High Availability RabbitMQ cluster as we already
> have RabbitMQ
> implementations and I feel that it is a far superior product to other
> MQs on the market.
> I understand that RabbitMQ doesn't work well over a WAN connection yet,
> however,

RabbitMQ *clustering* does not work well if the network can be 
partitioned. That's really what we mean by "avoid WAN clustering".

> with the Federation plugin becoming part of the distribution I believe
> this may change
> soon enough. Based on discussions I've read and participated in, I am a
> bit confused
> as to what is considered "WAN Clustering".  In my mind, two machines (or
> five) on
> one public /29 would not be considered to be connected over the WAN,

No, if they're on the same network segment then you should be safe.

> however, I was
> directed to the Federation plugin when I brought up connecting two
> public IPs.

This may have been a misunderstanding.

> Can someone please define "WAN Clustering", is it two machines connected
> on separate
> networks, in separate data centers?


> Basically, as I understand it, because MCollective is pointed to an IP,
> if that machine is down,
> there is no failover...  Maybe I'm just going about it wrong.

You need to either:

* Make sure that your clients can connect to one of several machines, in 
case one goes down.

* Use an IP load balancer in front of the cluster.

> A co-worker (literally moments ago) pointed out RabbitMQ now has a HA
> plugin that lays
> on top of a Rabbit Cluster.  I'll investigate this further.

This mirrors queues across nodes in the cluster. Prior to 2.6.0 queues 
were always tied to one node in the cluster and could thus form a SPOF.

> The wisdom of the MCollective group is to use ActiveMQ.  This is not an
> acceptable solution.

Clearly ;-)

Cheers, Simon

Simon MacMullen
RabbitMQ, VMware

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