AOS Load balancing. When?

I recently posted a question to one of the several news groups I subscribe too. The question was one in which I can't find a lot of material on, and I got a really great reply from another member of the group. With his permission I will now post my question and his answer. Hopefully this can help out people in the future.

My Question:

Hello All,

In light of my current progress to improve performance of Axapta, I am working through some idea's. I was wondering, what do you base load balancing for the AOS on? To explain further, what amount of users, or usage, etc. does one look at to say "You know what we need... we need to add another AOS and do load balancing!"

I am trying to find this out, but can't find much documentation on this. I am also really unsure of how to Google this topic, because it does not pull up much help.

Anyway, any advice on this topic would be great. Has anyone ever went from a single AOS to two AOS's load balanced?

thanks,
Brandon

Malcolm Burtt's answer:

Hi Brandon

Well, I guess you'd look at the following...

1. Is my AOS processor bound and not able to take additional processors?
2. Is my AOS memory bound and not able to take additional memory?
3. Is my AOS network bound and not able to take another network card?
4. Is my AOS disk bound (unlikely on an AOS) and disk performance not able to be improved?

If the answer to any of the above is "yes" and your AOS machine is not providing ant other service that could be relocated to another server then you need to ask.

Is it more cost effective to add a new AOS (and cluster the two) or replace my existing AOS with a better specified machine that will not suffer the same resource deficiency? Note that, if your server is not memory bound but your Ax32Serv process has hit its 2GB memory limit then you are effectively memory bound. If your server has more than 4Gb RAM (i.e. enough for 2 x 2Gb plus sufficient for the operating system to continue to function) and the processor capacity to handle the extra load then you could consider adding an extra AOS instance on the same machine and clustering the two instances.

You might also consider that adding a newer AOS might result in a slightly imbalanced cluster. AFAIK The AOS load balancing picks the AOS with the least number of users on it. So, if you have two machines and one is newer (and therefore likely to be higher specified) its possible that users one the newer AOS will receive a better user experience than those on the older machine. Its not a particularly big problem but might complicate things for you as your needs expand again and the performance starts to dip for some users but not others (i.e. "why the hell is user A complaining when user B is not and why the hell did user B complain yesterday when user A did not").

Good luck

Malcolm Burtt
Touchstone
Our Trusted Solutions - Your Optimised Business

I plan on doing a lot of research in this for 3.0 and 4.0 to see the major differences, and what Microsoft recommends. I hope to try to have a nice write up about AOS load balancing, how to make it happen, when you should add another AOS server, and what to look for. So look for that and more here on the X! (new nick name for this blog!)

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