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SAP Memory Parameters tuning after memory upgrade

Former Member
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Hello ,

Does anyone have a Standard SAP Notes or documents that involve tuning of essential memory parameters after memory upgrade from 6GB to 32GB? Anyhelp will be appreciated with reward points.

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Answers (3)

Answers (3)

Former Member
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Completed with suggestions on the post

JPReyes
Active Contributor
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Hi Basis lerner,

You can change following parameters at the instance profile using RZ10,

em\initial_size_MB

PHYS_MEMSIZE

System will need to be restarted

Hope this help!

Juan

Please reward points if helpful

Former Member
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Thanks Mike and Juan,

The installation is a R/3 4.6 and not NW2004. The parameters mentioned are the exact ones I am interested in. The help I am looking for is figuring the value for Buffer parameters including extended memory. The reason for memory upgrade is due to scenario all the WP always runs in PRIV mode and em is always 100% used. So any guideline in determining the value for those parameter would answer my question.

Thanks Again.

former_member192350
Active Participant
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It's called "tuning" and not "fixing" because it requires an itterative approach. You make some changes and see their effect, then make more changes, etc. Be careful not to change too many things at once.

As a starting point, I'd make sure you're using a 64-bit kernel; memory management is MUCH easier in a 64-bit environment. You don't mention the platform, but for example on Win32 you only have 2 GB available for the application (3 G if you use the /3G switch). Even if you run a 32-bit R/3 kernel in Win64, you get 4 GB avalailable to the application (much more if the R/3 kernel is also 64-bit!).

To make really good recommendations we'd need to get more information from you like the platform, 32-bit or 64-bit configuration, number of users, number of app servers, which modules are implemented, etc. Some things like buffer tuning can be addressed using logon load balancing if you have enough app servers.

As a VERY rough starting point, if you have a single instance (i.e. no app servers) and a 64-bit environment and all of that memory is for you, I'd bump your EM (em/initial_size_mb) up to 4G, set your ABAP buffer at 500G, and double anything that's showing a lot of swaps (more than 1,000 per day) in ST02. Then run for another day or two and see how things look....

Rich

Former Member
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Hello Rich,

Thanks for the guidance. I have gathered some information from my end which could be more helpful in tuning the memory.

The Environment is SAP 4.6B running on Oracle 8i on HPUnix 11 server. (64 bit environment). The central instance(DB + SAP Server) is a separate box and there is a dialog instance(SAP alone) running on a different server.

Avg Users are 210.

The CI where the memory upgrade is planning to be performed, the relevant parameters with their values are listed as below:

PHYS_MEMSIZE -> 64(displays that it is applicable only for Windows env)

em/initial_size_mb -> 5120MB

abap/heap_area_dia 2GB

abap/heap_area_nondia 2GB

abap/heap_area_total 2GB

ABAP buffer set to 500G(Not sure if you are referring to parameter abap/buffersize = 600000)

So all these parameter except buffer parameters from ST02 already have the suggested value.

Please suggest how much i can bump the em/initial_size_mb and others associated.

Thanks in Advance,

former_member192350
Active Participant
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Your PHYS_MEMSIZE looks low; that's normally used on NT servers and is usually set to the size of the host's physical memory, so that things like your EM buffer are sized automatically; there are several OSS notes about the parameter you might want to read about "Zero Administration Memory Management" or "ZAMM".

Your other buffers are pretty large for a CI as well; normally users are signing on to app servers, and not the CI (which needs to have some free DIA work processes for effecient enqueue management). In any case, those parameters look fine (5G EM, 600M abap buffer, 2G heap limits). You might want to read the following notes about memory management under HPUX:

33576, 37537, 43427, 106819, 100410, 113189

Finally, what makes you think you need to add memory to that configuration? You might be better served by adding some of that to your database (DB_BLOCK_BUFFERS); is your CI showing a lot of swapping in ST02? What makes you feel you should add memory to the CI configuration?

Thanks,

Rich

Former Member
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All depends on issues that were driving decision to make an upgrade from 6 GB to 32 GB. Do you have and use SAP J2EE applications? Or all memory belongs only for ABAP stack ?

Generally speaking I'd look into the following parameters:

1) Buffers (ST02)

2) Roll memory (e.g. ztta/roll_area)

3) PHYS_MEMSIZE

4) Memory for Garbage Collector (MS/MX and other) if J2EE is use.

Regards,

Mike