How to configure CA SystemEDGE to support variations of Free Memory on Linux

Products

• CA Systems Performance for IM (SystemEdge)

Issue/Introduction

How to configure SystemEDGE to support variations of Free Memory on Linux

Environment

SystemEDGE 5.7 & later

Resolution

Update the sysedge.cf with the line: 

linux_freemem_include buffers cached

Then save the file, and restart the agent.

• Linux free memory is calculated as total physical memory less memory in use. By default, memory in use includes system buffers and disk cache.
  
  
• Cached and system buffers can be reclaimed by the operating system if memory is needed for processes. For this reason, some choose to view free memory as including memory which is used by the operating system for caching or system buffers. 
  
  
• The linux_freemem_include directive includes these values in the Linux free memory calculation. 

The directive supports the following two options:

• buffers include system buffers in the free memory calculation.
  
  
• cached include cached memory in the free memory calculation.
  
  
• At least one of the previous options must be specified. The options may be specified in any order and must be separated by one or more spaces.

################################################################################
# This entry specifies the preferred calculation method (Linux only) for free memory.
#
# Syntax:
#    linux_freemem_include method [method]   (Linux only)
#
# Description:
#    <method> can be one or both of:
#    buffers = include system buffers in the free memory calculation
#    cached  = include disk cached memory in the free memory calculation
#
# Example:
#    linux_freemem_include buffers cached    (Linux only)
################################################################################
template linux_freemem_include <method-list>
linux_freemem_include buffers cached

Additional Information

SysEDGE will use output from /proc/meminfo to do the memory calculations.

For example:

MemFree:84592 kB+Buffers:380908 kB+Cached:3817392 kB = 4282892 (memfree)

memfree/total x 100 = Mem Used %

4282892/40396260 x 100 = 10.60%

• Not including buffers + cached for the SytemEDGE free memory calculations can cause inaccurate alarms\threshold triggers.