I've been questioned several times recently about AOS load balancing in Dynamics AX, and there seems to be quite a bit of confusion about how to properly configure AX for AOS load balancing, as well as high availability. Here are a few clarifications that apply to Dynamics AX version 4.0, AX 2009 and AX 2012:
- The AX client configuration determines which AOS instance that client will connect to.
- If multiple AOS instances are listed, it will simply go down the list until it establishes contact.
- If the contacted AOS instance is part of a load balanced cluster, that AOS will act as the load balancer. If not, the contacted AOS is used.
- The load balancing logic is based on a count of current user sessions, and also takes into consideration the max concurrent sessions defined for the instance on the cluster.
- If you have only one AOS instance listed in the client configuration, you have created a single point of failure. If no connection is established with that AOS, the client connection will fail, even if that AOS instance belongs to a cluster that has other AOS instances available for connection.
- Every client configuration should point to all AOS instances in the cluster, thus eliminating the single point of failure.
- Those AOS instances listed in the client configuration should belong to the load balanced cluster
- A dedicated load balancer should only be used in high volume scenarios