I am considering using a Network Load Balancer to load balance messages between my subscriber instances, instead of using the NServiceBus distributor (which is basically just a software load-balancer from what I can tell). Each subscriber instance will have a queue of the same name for messages to be delivered to, and there will be a virtual IP that round-robins between the subscribers. The publisher will only know about the virtual IP and queue name.
Here is what I understand as the pros and cons of doing this:
- PROS
- No need to install NServiceBus Distributor
- One less thing that would need to be managed/updated when we are scaling-out (we already use an F5 to load balance these machines, and our data center buys know it like the back of their hand)
- One less point of failure (yes, the NLB could fail, but let's face it, an F5 is going to be a lot more stable than NServiceBus Distributor running on Windows)
- No need to have a clustered server to have our clustered MSMQ. 2 servers is a lot more expensive than just adding another VIP to an F5.
- CONS
- The NServiceBus Distributor allows you to see the backlog of messages more easily since there is a single queue on the Distributor you can monitor. This makes it easy to know when you should add more worker nodes.
- The NServiceBus Distributor is smarter about controlling of number of worker threads, etc. Gives you more control than an NLB? (not sure about this one)
Have I captured this accurately? I know it is recommended to use the NServiceBus Distributor, and I would like to know more of why before I go against that recommendation.
