How to fix error: 452 4.3.1 Insufficient system resources Private bytes under pressure
Many people encounter Back pressure errors on their Exchange servers now and then, but when you have a recently new machine freshly installed and your email traffic is not that intense… How can you keep getting Private Bytes errors!?
Well, the answer is simple in many cases: Dynamic Memory
As you probably know, Dynamic memory is not supported or recommended by Microsoft to be used on any Exchange Server. What gives? Who doesn’t love Dynamic Memory? Well, Exchange was not designed with Dynamic memory in mind, but rather, it was designed to use all available memory it could get it’s hands on to improve performance.
So how come Dynamic memory is messing up with my Exchange this time?
I am not expert but the reason seems to be your initial memory allocated to your VM. Most likely Exchange considering it has a fixed amount of memory will initialize its counters and thresholds using a constant amount of memory. Given that scenario, it is no wonder that if you start your VM with 512 mb you can eat up your private memory quite fast even if your physical server has gigs and gigs of RAM. The issue went away when I started using normal (static) allocation of memory rather than dynamic. I also went as far as to play with my previous hypothesis and it worked. I assigned a “high” amount of dynamic memory to start the system with and then dynamic memory takes some of it away if it is IDLE. This has worked fine with me but I would recommend following Microsoft’s recommendations and using static memory. I kind of like living on the “edge” lol.
Hope this helps!