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SAP OS Monitor

SAP OS Monitor

Operating System Monitor ST06/ST06n/OS07n provide the following functions to analyze the bottleneck for CPU, Memory, file system, LAN, etc.


The CPU utilization for a non-virtualised environment will always sum up to 100%. User utilization should not exceed a value of 50 to 60%. System utilization should be below 20% and Idle time should be above 20%. An idle time below 20% will lead to CPU bottleneck situations. IO Wait time is considered a subset of idle time. It can’t be concluded that a high IO wait time indicates a disk-level issue. IO Wait time includes block IO, raw IO, or Virtual Memory operations such as paging/swapping. It does not include time spent on tape IO or terminal IO.




• Physical memory: This number gives the size of the RAM of the server.
• Swap size: Configured swap size: This is the sum of physical RAM and swap/page space. This sum is also known as virtual memory in SAP systems.
• Swap size: Maximum swap size This figure gives the amount of configured swap/page space.
• Page: The swap/paging activity on OS level per hour should not be higher than one-fourth the size of the physical RAM for Page in activity on Windows OS, or one-fifth the size of the physical RAM for Swap Out activity UNIX OS. Otherwise, you will observe a decrease in SAP system performance caused by heavy CPU and I/O utilization.


Related SAP Notes:

  • 2442188 - decision tree - Analyzing and Configuring Memory to Increase Performance
  • 1121904 - SAP on AIX: Recommendations for paging space
  • 103747 - Performance: Parameter recommendations as of Release 4.0
LAN check by PING

In the operating system monitor (Transaction ST06), select Other Functions • LAN Check by Ping or call the transaction code:OS01.

Please see the following note for further information

For how to use LAN Check By Ping


Hardware monitoring

There are a number of tools that are available to collect data on your hardware utilization.

SDF/MON - Performance monitoring
The transaction SDF/MON is a powerful in-built feature in all SAP systems that can help collect hardware performance metrics from a number of areas;

  • CPU Utilization
  • Pages in/Pages out
  • Extended memory utilization
  • Paging memory 

You can set the performance monitor for a daily schedule or for a specific time when the a performance issue is known to occur. This is defaulted to take a snapshot of the system perfromance every 10 seconds. One very useful feature of SDF/MON is viewing the snapshot data in real time allowing for analysis as the issue occurs.

More information about SDF/MON can be found here; 2383809 - How to use the SDF/MON tool to analyse performance issues.

Another useful feature is importing the SDF/MON data into a tool called RSORASTT which can graph the outputs for further analsysis.

The tool can be found in the attachements of the following note; 1299493 - Loadable SAP Support Monitors

The graph below displays SDF/MON data collected for a defined time period where cpu idle%(1) is graphed for a selected server(2). This is very helpful as servers can be selected as required. In this case, the cpu idle% does not go below 80% and therefore is acceptable (3).

Nmon - Performance monitoring for AIX and Linux OS systems

The Nmon tool is a very useful too for giving detailed information on OS/hardware performance for AIX and Linux systems. The Nmon tool collects the hardware performance for output to a .nmon file. This file can then be analyzed by the Nmon analyzer which displays the following;

  • CPU utilization
  • Disc write speed
  • OS/system utilization vs. User utilization

If analysis is taking place on virtualized environment, it is critical that enhanced monitoring functions are activated as per the SAP Notes highlighted below:


  • 994025 - Virtualized OS environments in the operating system monitor
  • 536954 - OS data in a cluster environment for OS07
  • 1084019 - OS07N: New operating system monitor
  • 2067546 - ST06/OS07N: Overview note


  • 2447884 - VMware vSphere with VMware Tools 9.10.0 up to 10.1.5: Performance Degradation on Windows
  • 2161991 - VMware vSphere configuration guidelines
  • 1055767 - Best Practises VMWARE ESX


  • 1409608 - Virtualization on Windows
  • 1056052 - Windows: VMware vSphere configuration guidelines


  • 1122387 - Linux: SAP Support in virtualized environments
  • 1122388 - Linux: VMware vSphere configuration guidelines


  • 1379340 - Extended set of virtualization metrics for AIX Power Systems 

Oracle & Solaris

  • 2031893 - Virtualization monitoring with saposcol on Oracle Solaris 
Other related Notes/Links






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