[chef] Re: Configuration for Chef to have high availability, mirrored queues.

[Brad Knowles < >]

On Oct 27, 2011, at 2:06 PM, 

 
 wrote:

> By any chance, is there a way to configure Chef to create HA mirrored 
> queues? That is to say, is there a way to pass a configuration setting 
> rather than editing the amqp files directly? I was reading up on 
> implementing RabbitMQ HA (http://www.rabbitmq.com/ha.html#genesis) and 
> figured a homogenous HA policy would be great to have for all our services 
> interacting with the RabbitMQ servers.

This is more of a question on the chef-server internal side and how it 
interfaces with RabbitMQ, as I don't think it affects chef-solo or 
chef-client.


However, do keep in mind that mirrored queues are very new, and if you've 
been monitoring the rabbitmq mailing list lately you will have noticed that 
the author (or at least one of the contributors) of this code has done some 
profiling and confirmed that mirrored queues will suffer a roughly 
order-of-magnitude (base 10) performance hit over non-mirrored queues.  This 
is for non-durable queues, btw -- I don't know what kind of performance hit 
you'd see for durable queues that are mirrored.

From what I've been able to tell, this is a side-effect of the algorithms 
that are used to implement mirrored queues, which in three different sections 
of the code you get three write operations performed for each write operation 
that would be performed for non-mirrored queues.  So, unless the algorithm 
can be improved, this seems like an inherent performance hit that you're not 
going to be able to avoid.

Just something to keep in mind.

-- 
Brad Knowles 
<
 >
SAGE Level IV, Chef Level 0.0.1