Memory parameter.

[ganesh_borase2]

Hello everybody,

I installed the ECC 5.0 with windows 2003 (64-bit) + SQL server 2005 with 32 GB memory.

Database size is 350 GB ( migrate from 32-bit to 64-bit).

Now, I want to configure the memory parameter for performance view.

Please suggest me memory parameter and how to calculate their values?

which parameter will effect on performance?

Also suggest PHYS_MEMSIZE value...

Thanks

Ganesh

[Sriram2009]

Hi ganesh

PHYS_MEMSIZE parameter values are in MB if you give more then you physical memory it will throw the error message. Better you can check the SAP note 88416 ZERO Memory Administration its very important to set the values in windows base servers

Regards

Sriram

[Sriram2009]

Hi ganesh borase

As per the SAP ZERO Memory Administration-88416

Regards

Sriram

[Former Member]

Hi Ganesh,

This is really a big and subjective topic, you need to understand the concept and read a lot. Try to browse help.sap.com and sap notes as well.

For e.g. consider these links and their subtree pages -

https://help.sap.com/saphelp_nw04s/helpdata/en/d1/80b716dc8111d2ac8f0000e83539c3/content.htm

https://help.sap.com/saphelp_nw04s/helpdata/en/02/96268c538111d1891b0000e8322f96/content.htm

PHYS_MEMSIZE is the total RAM assigned to a particular SAP system. Whenever if you need to add some more RAM to particular SAP SID then PHYS_MEMSIZE is the parameter you need to update. Just by adding more RAM to the physical host will not reflect into SAP if we don't update this parameter.

https://help.sap.com/saphelp_nw04s/helpdata/en/84/7ed384d81f11d188be0000e83539c3/content.htm

Thanks

[ganesh_borase2]

Hi!

if we have 32 GB RAM so what should value of PHYS_MEMSIZE that

will help to improve performance.

Also there is any rule to configure the work process distribution?

Thanks

Ganesh

[Former Member]

Hi Ganesh,

32GB RAM is I think the physical RAM on the host you are referring to.

Nowadays, 16 GB is the minimum RAM recommended for SAP system installation and rest depends on the sizing and load etc.

First check what is the current value of PHYS_MEMSIZE you have for your SAP system, using RZ11 ( if not set in RZ10 yet). That value is the one which was used during this SAP system installation, if no one edited it after that.

There is no thumb rule for the distribution of Memory for the work process, but obviously as the number of work processes increases - memory requirement increases. For e.g. sometimes if we have less amount of RAM on dev or qa box then we can keep less number of sap work processes in that particular SAP system.

How memory allocation works in detail, please go through -

http://help.sap.com/printdocu/core/Print46c/en/data/pdf/BCCSTMM/BCCSTMM.pdf

Normally SAP Roll Area, extended memory and private memory individually constitute the allocation for a user context/work process.

Thanks

[Former Member]

I found a guide from SAP, very useful one, we used to study similar ones -

http://www.sap-press.de/download/dateien/2382/sappress_sap_performance_optimization_guide_6..pdf

Thanks

[ganesh_borase2]

Hi!

yes, I am referring to (32 GB) physical memory RAM on server.

Now currently in profile PHYS_MEMSIZE = 18000.

So Can I change this value upto 24000

I read in document for PHYS_MEMSIZE you have to set value which you want

to assign for the SAP.

Thanks

Ganesh

[Former Member]

Hi!
> yes, I am referring to (32 GB) physical memory RAM on server.
> Now currently in profile  PHYS_MEMSIZE =  18000.
> So Can I change this value upto 24000
>  I read in document for PHYS_MEMSIZE you have to set value which you want
> to assign for the SAP.  
> 
> 
> Thanks
> Ganesh

Hello Ganesh,

Yes, you can set it to 24000, default value is in MB.

Since, your CI and DB are on same host, so normal rule can be applied as - To assign around 60-70 % to CI (i.e. SAP) and 40-30% to DB and at the same time we should leave a bit of memory for OS as well - for e.g. 1 or 2 GB.

So, in your case 24 GB would be OK for SAP. But after assignment of this increased memory to SAP instance (after you are done with the update of PHYS_MEMSIZE) then you please start planning to modify/update other Memory parameters [For e.g. em/max_size_MB etc.] to 'utilize' this more available Memory to SAP instance.

Thanks

[ganesh_borase2]

Hi!

Thanks for reply.

I read SAP NOTE 1518419 - Page file and virtual memory required by the SAP system

This recommend/sugges

PHYS_MEMSIZE is the available main memory for the SAP instance; by default this value equals the available RAM size. If you want to limit the main memory used for the SAP instance, you can change this parameter in the instance profile.

So please suggest value for parameter PHYS_MEMSIZE

and I will set the value for other parameter as per SAP Note 88416 - Zero administration memory management for the ABAP server

Please suggest....

Thanks

Ganesh

[Former Member]

> 

PHYS_MEMSIZE is the available main memory for the SAP instance; by default this value equals the available RAM size. If you want to limit the main memory used for the SAP instance, you can change this parameter in the instance profile.

> 

Hello Ganesh,

Exactly what I indicated in previous post, just assign 60-70% of total RAM to the SAP instance. Accordingly 24 GB out of 32 GB is OK.

Obviously we should not use whole of available RAM (physical RAM) just for SAP instance when we have SAP and DB instance both on the same host + a bit of memory for OS.

So, to limit the memory to be used by the SAP instance we explicitly set the parameter PHYS_MEMSIZE in the instance profile.

Just for information - When new SAP system is installed, at that moment the SAPinst program just distribute the total RAM equally into two parts - half for SAP instance and rest for DB instance (ONLY if we do not modify the default value chosen by sapinst program at that moment). That's how, at that moment, SAPinst sets the default value of PHYS_MEMSIZE parameter which you are able to see in RZ11.

If DB is not on the same host, i.e. only SAP CI is there then you can use whole of the physical RAM just for that 'SAP' instance, because DB instance is on different host.

I would say, please go for 24 GB.

Thanks

[ganesh_borase2]

Hi!

when I am trying to set the value PHYS_MEMSIZE to 24000 it give the error

PHYS_MEMSIZE greater than maximum 20000.

Please suggest How to set the value to 24000? (Server has 32- GB RAM, 20000 GB Swap space, OS- Windows 2003 64-bit)

Thanks

Ganesh

[Former Member]

Hi Ganesh,

I think the page file size (swap space - 20GB) is setting up the limit on this parameter.

Once verify the current value of em/max_size_MB in your SAP system, for zero administration in Windows it might be currently 20000 MB and probably due to which you are not able to set phys_memsize greater than 20000 MB. I think this is the way how zero administration for memory management is set up for Windows platform installations.

I would say you try to increase the swap space/em/max_size_MB and then phys_memsize.

https://help.sap.com/saphelp_nw04s/helpdata/en/84/7ed384d81f11d188be0000e83539c3/content.htm

https://help.sap.com/saphelp_nw04s/helpdata/en/84/7ed387d81f11d188be0000e83539c3/content.htm

Thanks

[ganesh_borase2]

hi,

I have only set phys_memsize parameter

and not set any value for the following

em/initial_size

em/max_size_MB

em/address_space_MB

Thanks

Ganesh

[Former Member]

Hi Ganesh,

Seems you have to increase the swap space first, as my previous post help.sap.com link tells -

The basis for zero administration memory management is a sufficiently large Windows page file. The previous recommendation still remains:

Windows page file = 3 to 4 times the main memory size

Thanks

[ganesh_borase2]

Hi!

Actually, after setting the SWAP space to 20 GB I set the PHYS_MEMSIZE parameter value to 26000 but it generate error

Thanks

Ganesh

[Former Member]

That's what I think you need to increase the swap space to some more value as per rule - swap = 2 or 3* RAM

Thanks

[ganesh_borase2]

Hi!

when I check in RZ11, the values for PHYS_MEMSIZE is

minimum 32

maximum 20000

Please suggest..

Thanks

Ganesh

[Former Member]

Hello Ganesh,

I just verified from some of our landscapes,

It seems it is the restriction for ECC 5 system. I just checked in one our ECC5 system and it shows just the same as yours and when I checked in one of our ECC 6 system - it shows minimum as 32 and maximum as 64000 !

Thanks

[ganesh_borase2]

Hi,

Then can we assume in ECC 5.0 for parameter PHYS_MEMSIZE only 20 GB allowed?

when I check the table for the same (TPFYPROPTY) it allow change the min and

max value for the same. if we change here then can change value for the same greater

than 20 GB in profile. But can it really use the memory greater than 20 GB.

Thanks

Ganesh

[Former Member]

Hello Ganesh,

That we should confirm from SAP once.

Thanks