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Yep...the difference is small but significant.
In your case you're telling everyone who has more than 30 concurrent users they have to cluster.
In my case I'm saying "don't worry, no issues until you hit more than 60+ concurrent users".
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Nope. I never suggested that. I just suggest that you utilize more memory on your 64Bit OS for each concurrent user.
I have never, ever recommended clustering for EnterpriseOne Web users. I do recommend using Webtier Utilities together with a realistic load balancer. My suggestion is that ALL customers consider using a loadbalancer - whether its an open-source load balancer like Zen - or a hardware load balancer. It just makes sense, and can provide a LOT more cost effective solution since it provides high availability between users.
ok - heres a nice little chart that explains all. I only work these days with 64bit JVM's on 64bit OS - I'm not expecting any of my customers to be using 32bit anything these days. I'm also never going to suggest implementing E1 HTML on anything less than 2 cores. Therefore, heres an interesting sizing chart :
32 users : 1 64bit JVM : 2Gb MaxHeap : 2 CPU Core
64 users : 1 64bit JVM : 4Gb MaxHeap : 2 CPU Core
128 users : 1 64bit JVM : 8Gb MaxHeap : 4 CPU Core
256 users : 1 64bit JVM : 16Gb MaxHeap : 8 CPU Core
512 users : 1 64bit JVM : 32Gb MaxHeap : 16 CPU Core
1024 users : 1 64bit JVM : 64Gb MaxHeap : 32 CPU Core
So, with my chart above, you can see that in THEORY you can have 1000 users on a single 64bit JVM with 64Gb memory and 32 available cores - but in reality, you'd probably hit issues with very long Garbage Collection timing issues above 8Gb.
Lastly, and this is more important to production use, you probably want more JVM's to isolate any issue that might develop with a single JVM and to ensure that less users are impacted by a single system failure.
A better way to look at the above is the following :
32 users : 1 64bit JVM : 2Gb MaxHeap : 2 CPU Core
64 users : 1 64bit JVM : 4Gb MaxHeap : 2 CPU Core
128 users : 1 64bit JVM : 8Gb MaxHeap : 4 CPU Core
256 users : 2 64bit JVM : 8Gb MaxHeap ea: 8 CPU Core
512 users : 4 64bit JVM : 8Gb MaxHeap ea: 16 CPU Core
1024 users : 8 64bit JVM : 8Gb MaxHeap ea: 32 CPU Core
If you are using 16core CPU machines, then you can have 1024 users spread across 2 machines, each running 4 JVM's - and will use 32Gb on each after the OS, together with a loadbalancer ensuring that all user sessions are round-robin balanced between the 8 JVM's.
So, after all that, my chart is still a good yardstick - without fully understanding what type of transactions the users are performing.