sap page file vs. physical paging volume

[Former Member]

Hello,

We have the sap page file PAGFIL00, this file is located in /usr/sap/<SID>/DVEBMGS00/data/.

Also we have two physical page volumes in the system. We can browse them by command lsps and we see that these volumes are almost always filled less then quarter. But the sap page file  size constantly increases.

1) What is the use of the sap page file?

     I cannot understand when we should say about this sap page file and physical paging space at the operating system level.

2) What's  the difference between these two paging areas?

3) Why the sap page file is located in /usr/sap instead of in paging space of operating system? What are paging volumes for???

4) And finally what the sap system located in its page file and what it is located on paging volumes?

Can anyone clear to me this matter?

Thank you very much!

[former_member197561 · Accepted solution]

Dear Igor,

This documentation answers your question:

http://help.sap.com/saphelp_banking463/helpdata/en/02/962735538111d1891b0000e8322f96/frameset.htm

"

Memory Management (BC-CST-MM)

SAP Paging involves the allocation of memory for the current internal session by transferring pages out of memory, similarly to operating system paging.

SAP Paging enables the roll area to be extended at ABAP runtime when a large dataset, internal tables, for example, is handled.

SAP's memory management concept currently limits SAP Paging to cases where the ABAP commands EXTRACT and EXPORT... TO MEMORY... are used.

"

See related http://scn.sap.com/thread/1371099 (MEMORY_NO_MORE_PAGING)

Best Regards,

Sylvia

[former_member191911]

Hi Igor,

The SAP page file is being used for ABAP specific operations, such as extracts, and context independent objects such as exports.

This page file is shown on the operating system as a normal file, it has no attribute for OS  paging or what so ever.

The fact that this file is stored in /usr/sap/.. etc. is to make sure that this file is part of the SAP system.

In case your SAP extended memory gets exhausted or some process on OS is running wild, the system can allocate OS paging space.

Hope this answers your question!

Kind regards,

Mark