Utility Program ESMON Improves System Performance by Allowing You to Analyze Memory Allocation
- by Vipul Shah, SAP Basis Consultant, Performance Analyst
- April 8, 2011
Efficient analysis of memory allocation to SAP users is really important. The utility program ESMON is all about tracking down every detail of memory that is being used. See how to analyze any memory leak or blocked memory using ESMON.
ESMON is the utility program that tells you every detail of memory allocated to users, with ES representing extended shared segments and MON representing monitor. You need to run command “esmon pf=<INSTANCE_PROFILE> <command line option>” as <SID>adm user. It is standard SAP functionality and works with all SAP systems running on an AIX 64-bit kernel.
Most performance problems come from memory issues. It is a common misconception that whenever any transaction runs in an SAP system, memory is mainly controlled by only two parameters — ZTTA/ROLL_EXTENSION and EM/TOTAL_SIZE_MB. This is not quite true. Although these parameters are important, you also need to be aware of additional parameters to ensure optimal memory use. You can avoid these memory issues if you know how best to use extended shared memory segments (ES) parameters.
The ES layer concept was introduced for AIX 64-bit kernels where memory allocation can be controlled at a detailed level — for example, in addition to quota, you can also control segments and memory blocks. With the ES layer implemented, you gain a lot of flexibility and control over memory allocation to the SAP system and releasing back to the operating system. One of the advantages of using the ES parameters is that they provide control over how the system uses memory, speeds up the system performance, and allocates memory to users. ES segments only disclaim memory when it is necessary to free up the physical memory.
While it is more flexible and allows more control, the ES layer is also more complex, requiring closer monitoring of its behavior during problematic situations such as an extended memory bottleneck or overconsumption of quota. That’s where the utility program ESMON comes into play: This is where you can get complete details on the behavior of memory consumption by the SAP system over the ES laye
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