Handy Tips #30: Detect continuous increase or decrease of values with monotonic history functions

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Zabbix Certified Expert & Trainer

May 26, 2022

Analyze your incoming metrics and look for interruptions in continuously increasing or decreasing metrics with the monoinc and monodec history functions. A continuous increase or decrease is the norm for metrics such as server uptime, time remaining until a task is executed, number of daily transactions, and many other such use cases. A software or […]

Analyze your incoming metrics and look for interruptions in continuously increasing or decreasing metrics with the monoinc and monodec history functions.

A continuous increase or decrease is the norm for metrics such as server uptime, time remaining until a task is executed, number of daily transactions, and many other such use cases. A software or hardware failure could impact these counters and we need to ensure that they are providing the data in an expected manner.

Use monoinc and monodec history functions and detect if value monotonicity is true or false:

Detect monotonicity over a number of values or a time period
Strict and weak modes of monotonicity detection

Receive alerts if a metric is not monotonic
The monotonicity check can be combined with other functions to create flexible problem generation logic

Check out the video to learn how to use the monoinc and monodec history functions

How to configure monoinc and monodec history functions:

Identify the items for which you wish to detect monotonicity
For this example, the system.uptime key is used
Navigate to Configuration → Hosts → Your host → Triggers
Press the Create trigger button
Provide the trigger name and severity
Press the Add button to add the trigger expression
Select the item, the monoinc function, evaluation period, mode and result
For this example, we will use the strict mode
An example expression: monoinc(/Linux server/system.uptime,1h,”strict”)=0
Simulate a problem by restarting the host
Navigate to Monitoring → Problems
Confirm that the problem has been generated

Tips and best practices

The functions return 1 if all elements in the evaluation period continuously decrease or increase, 0 otherwise
The default mode – weak, checks if every value is bigger/smaller or the same as the previous one
The strict mode checks if every value has increased/decreased
Relative and absolute time shifts can be used to analyze time periods for monotonicity