RabbitMQ high memory usage and I/O write/sync

The bounty expires in 7 days. Answers that other users post to this question are eligible for a +100 reputation bounty. Odrai wants to draw more attention to this question:

Dear Stack Overflow user, I am seeking guidance to address an issue where the memory usage continually increases, even with a new installation of RabbitMQ and a simple .NET project utilizing quorum queues. I am requesting assistance to identify and resolve the root cause of this problem.

I’m currently using the RabbitMQ (3.10.25) in production with 3 nodes and contains several queues:

  • one classic queue
  • one quorum queue (to handle nservicebus commands - NServiceBus.RabbitMQ package 8.0.2)
  • one quorum queue ‘error’
  • 28 nservicebus quorum queues (nsb.v2.delay-level-xx)

The classic queue handles 2 messages per second. The quorum queues do nothing.

After a few hours one node is still stable (used by the classic queue), the other 2 are high on memory usage. The watermark memory limit has been reached. In addition, there is a lot of preallocated unused memory (seems not normal and still increasing). Tables other is 1.2GB as well… (keeps increasing)

What is the best approach to tackle this issue? Is there a (common?) setting to reduce the memory usage?

Some info is available at RabbitMQ, but it is unclear which settings need to be adjusted as starting point.

I kindly invite you to review my post on Stack Overflow.