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memory-usage

README.rst

Check memory-usage

Overview

Displays the amount of free and used memory in the system and checks how much physical memory is left across platforms by using the available field.

Hints:

  • Be aware of the differences in memory counting between different tools like top, htop, glances, GNOME System Monitor etc.
  • Memory counting also changed between different Linux Kernel versions.

Fact Sheet

Check Plugin Download https://github.com/Linuxfabrik/monitoring-plugins/tree/main/check-plugins/memory-usage
Check Interval Recommendation Once a minute
Can be called without parameters Yes
Compiled for Linux, Windows
3rd Party Python modules psutil

Help

usage: memory-usage [-h] [-V] [--always-ok] [-c CRIT] [--top TOP] [-w WARN]

Displays amount of free and used memory in the system, checks against used
memory in percent.

options:
  -h, --help           show this help message and exit
  -V, --version        show program's version number and exit
  --always-ok          Always returns OK.
  -c, --critical CRIT  Set the critical threshold for memory usage (in
                       percent). Default: 95
  --top TOP            List x "Top most memory consuming processes". Default:
                       5
  -w, --warning WARN   Set the warning threshold for memory usage (in
                       percent). Default: 90

Usage Examples

./memory-usage
./memory-usage --warning 90 --critical 95

Output:

36.2% - total: 3.8GiB, used: 1.1GiB, available: 2.4GiB, free: 989.4MiB
shared: 41.6MiB, buffers: 3.6MiB, cached: 1.8GiB

Top5 most memory consuming processes:
1. php-fpm: 810.7MiB (20.7%)
2. forkit: 418.3MiB (10.7%)
3. kit_spare_001: 335.5MiB (8.6%)
4. mariadbd: 306.2MiB (7.8%)
5. icinga2: 63.8MiB (1.6%)

States

  • WARN or CRIT if total memory usage is above a given threshold.

Perfdata / Metrics

Name Type Description
available Bytes The memory that can be given instantly to processes without the system going into swap. This is calculated by summing different memory values depending on the platform and it is supposed to be used to monitor actual memory usage in a cross platform fashion.
buffers Bytes Cache for things like file system metadata (Linux, BSD).
cached Bytes Cache for various things (Linux, BSD).
free Bytes Memory not being used at all (zeroed) that is readily available; note that this doesn't reflect the actual memory available (use available instead). total - used does not necessarily match free.
shared Bytes Memory that may be simultaneously accessed by multiple processes (Linux, BSD).
total Bytes Total physical memory (exclusive swap).
usage_percent Percentage  
used Bytes Memory used, calculated differently depending on the platform and designed for informational purposes only. total - free does not necessarily match used.

Troubleshooting

This checks sometimes reports > 100% memory usage
That's fine, the RES column in top says the same if you sum up all values for a process (attention: the values in top's RES column are KB by default), and compare process memory to total physical system memory. The machine does not swap, so this is kind of Linux memory management mystery.

Credits, License