Extended Memory parameters

[Former Member]

Hi,

We have installed 4 SAP components(R/3,Xi,EP,BIW) on single OS (HP-UX)with Oracle. System perfectly working but little bit poor performance.

During installation we have given 8GB memory for all the compoennets , that means each instance 2GB ( 60:40 rule - 1.2GB for Application server ,0.8GB for DB)

All the instances we have installed same . Now we are planing to upgrade extended memory 8GB to 32GB (approx 4times of previous memory)

Now my concern is if i increase extended memory 8GB to 32GB , how it will effect to SAP applications.

Should i go and change instance profile parameters ?

Which profile parameters i should change ?

And what is the memory caluculation proportionality rate for my previous and upgrade memory?

I should change all the 4 components ?

Is there any problem if i change wrong parametrs ?

Please suggest .

Thanks

Lisa

[Former Member]

Hi Tim,

Thanks for your explantion.I have installed as each instance have its own oracle instance. No sharing databse.

I understand your explantion , but iam still concern about what are the paramertes we need to change and how much?

-Lisa

[Former Member]

Lisa,

The most important thing to calculate here is the allocation for each component. For XI, for instance, you need to accommodate for the ABAP and J2EE stacks, remembering that the J2EE stack does very poorly if it leaves physical memory.

Additionally, are you running the Oracle DB as MCOD, or does each component (XI, BI, EP, etc) have it's 'own' instance of oracle?

Let's take XI as an example. If you were to take the memory to 8GB, an approximate sizing would be 3.6GB for the ABAP stack, 2.4GB for the database, and 1.5 GB for the J2EE stack (1024 for each server you have, assuming here you have 1 server0 running. I'm also sizing 0.5GB for server overhead for other processes that need to run.

For R/3, BI and EP, the sizing is more simple. If neither R/3 (ERP?) or BI have an java stack, then 60/40 is a good place to start. Remember that with EP, the server0 stack really does not benefit from an unlimited memory allocation. You should really stick to SAP recommendations of 1024MB for the server0 process. (so you may not be able to fully allocate extra storage to the portal apps, but you may still see improvement because the overall system resources are less constrained.

When you are sizing, here are a couple of quick points to get you started. It all has to do with what the system is made of (1) ABAP - A (2) Java - J or (3) ABAP and Java A+J

1) For an A system, 60/40 can still be used as a good staring point.

2) For a J, allocating more than 1GB per server node will not neccessarily do you much good. The bottom line for J stacks is to keep everything in memory and out of swap.

3) For an A+J system, you should take the total memory of the box, (8GB) subtract 0.5GB for the dispatcher and 1GB for each server node. So in this case, assuming 1 server node, you'd take 8GB and subtract 1.5GB. This remaining memory is your 60/40 rule.

This will not answer everything, but I've found it a good discipline in starting to do sizing and performance tuning.

I hope it helps!

[Former Member]

depends on how many users/load on each sap component

[Former Member]

Hi Siva,

Thanks for your reply. What is the proportionality rate i can assign.

Lisa

[Former Member]

WAS uses zero memory management so all u havr to do is change the parameter PHYS_MEMSIZE in all the instance profiles to use uo the new memory .and restrat the sap instances