Must msmq queues be transactional?

Question

I've just recently gotten into using Rebus, and noticed that it always creates transactional msmq-queues resulting in heavy traffic to the HDD (0,5 - 5mb/sec). Is this intentional - and can something be done to avoid it?

Answer 1

It's correctly observed that Rebus (with its default MsmqMessageQueue transport) always creates transactional MSMQ queues. It will also refuse to work with non-transactional input queues, throwing an error at startup if you created a non-transactional queue yourself and attempt to use it.

This is because the philosophy in Rebus revolves around the idea that messages are important data, just as important as the data in your SQL Server or whichever database you're using.

And yes, the way MSMQ implements durability is that messages are written to disk when they're sent, so that probably explains the disk activity you're seeing.

If you have a different opinion as to how you'd like your system to treat its messages, there's nothing that prevents you from replacing Rebus' transport with something that can work with non-transactional MSMQ. Keep in mind though, that all of Rebus' delivery guarantees will be void if you do so ;)

Answer 2

We had the very same observation, the annoying aspect is that we have 300/500 KB/sec write on disk even when there are no message on the queue. It seems that only polling from the queue causes a constant write on disk.

Gian Maria.