[rabbitmq-discuss] RabbitMQ mirrored queues and node failure

Matthias Radestock matthias at rabbitmq.com
Wed Nov 16 21:55:56 GMT 2011

On 16/11/11 21:44, Major Hayden wrote:
> 1) Does C come back up with the 10 messages that it had on it before
> it failed?
> 2) What happens to those 10 stale, old messages that node C had on it
> before it failed (that were already picked up from nodes A and B by
> consumers)?

 From http://www.rabbitmq.com/ha.html#start-stop

when a slave rejoins a mirrored-queue, it throws away any durable local
contents it already has and starts empty. It's behaviour is at this
point the same as if it were a new node joining the cluster.

Btw, ...

> While repairs are being made to C's rack, consumers still talk to
> nodes A and B to pick up and drop off messages.  Let's say the queues
> on A and B are reduced to zero several times while C is offline and
> then C comes back online.

I think you may have misunderstood the master/slave behaviour of 
mirrored queues. From http://www.rabbitmq.com/ha.html#behaviour

All actions other than publishes go only to the master, and the master 
then broadcasts the effect of the actions to the slaves. Thus clients 
consuming from a mirrored queue are in fact consuming from the master.



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