[rabbitmq-discuss] Rabbitmq cluster design and HA

Michael Klishin mklishin at gopivotal.com
Tue Apr 29 09:13:54 BST 2014

On 29 April 2014 at 07:22:03, srikanth tns (srikanthtns at gmail.com) wrote:
> > Can you let us know what would be optimal settings on rabbitmq  
> cluster to prevent it from crashing and having reliable messaging?  

It's really hard to make general recommendations without knowing what
kind of workload you use.

> 1) sysctl configurations

nlimit > 20,000 or so (definitely can't be less than ~ 6K)

> 2) Disk limitations to setup on cluster . the default is 50MB

I'd use 500 MB or so if RabbitMQ is the primary thing that runs on the machine.

> 3) Memory to used , right now its default 40%

Can be up to 90%, again, depending on what else may run on the same machine.

> 6) any disk space limitation on the hosts

Host is this different from 2) above?

> For HA , we are using ha-mode all to duplicate the queues across  
> all nodes in the cluster. Do you think its reliable during the  
> failover scenario ?During the failover it would like 100k queues  
> on nthe new master? Or should we use ha-mode = exactly/nodes ?  

With 3 nodes ha-mode=all is a reasonable amount of duplication. If you are confident
you will never lose more than 1 node at a time, use ha-mode=exactly with 2 nodes.
Less duplication means better throughput.

As to how well new master election will work with 100K queues, try it. 

Software Engineer, Pivotal/RabbitMQ

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