Creating a Custom Metric to Check if a Linux Filesystem is Mounted

Some filesystems are critical to a business, such as those used in interfaces. This custom metric group will alert if a filesystem is not mounted.

Create the Bash Script to Check the Filesystem Status

Firstly, we need to create a bash script that takes the filesystem as its input argument and then checks its status. Create the following script called /sbin/ (owner is root, permissions 755). You may put this script somewhere else if you prefer, but be sure to refer to the correct location later on in this post.

findmnt $1 >/dev/null && echo \{type:integer, name:FileSystemMounted, value:1\} || echo \{type:integer, name:FileSystemMounted, value:0\}

The findmnt command returns the mount details if the filesystem is mounted. The filesystem is passed as a script argument in variable $1. If the filesystem is mounted, the script returns integer 1. If the filesystem is not mounted, the script returns integer 0. For example, to check your desired filesystem, execute it like this as root:

/sbin/ /the/filesystem/you/want/to/check

The output will be in JSON format. If the filesystem is mounted, the value will be 1, as follows:

{type:integer, name:FileSystemMounted, value:1}

The name:FileSystemMounted is the name of the value to be picked up by saphostctrl, as described next.

Create the Custom Operation for saphostctrl

To load these values into Focused Run, we create a custom operation for saphostctrl. Create the following custom operations conf file:


This contains:

Command: /sbin/ $[FILESYSTEM]
Workdir: /home/sapadm
Description: Check if filesystem is mounted
ResultConverter: flat
Platform: Unix

To test the custom operation, execute the following command:

/usr/sap/hostctrl/exe/saphostctrl -function ExecuteOperation -name checkfilesystemmounted FILESYSTEM=/the/filesystem/you/want/to/check

The result should be as per the following example:

Webmethod returned successfully
Operation ID: 0A02C69098121EDDA68C041B50FE858D

----- Response data ----
description=Check if filesystem is mounted
{type:integer, name:FileSystemMounted, value:1}

Create the Custom Alert in SAP Focused Run

In Focused Run, we create an alert in a Linux host monitoring template. For example, the alert name is “Interface Filesystem not Mounted”. The Alert should be in Category “Exceptions” and the Severity is up to you. In this case it is 9.

Create the Custom Metric Group in SAP Focused Run

Next, we create the custom Metric Group . A Metric Group allows variants to be created, and each variant corresponds to a filesystem you wish to monitor.

Overview Tab:
  • Name: “Interface Filesystem not Mounted”
  • Category: Exceptions
  • Class: Metric Group
  • Data Type: Integer
Data Collection Tab:
  • Data Collector Type: Diagnostic Agent (push)
  • Data Collector Name: OS: ExecuteOperation
  • Collection Interval: 5 Minutes (depending on the criticality)
  • CUSTOM_OPERATION_NAME: checkfileystemmounted – This corresponds to the custom operation for saphostctrl created earlier
  • METRIC_NAME: FileSystemMounted – This corresponds to the name of the metric in the JSON output by the bash script
  • RETURNFORMAT: JSON – This is the output format of the bash script
Usage Tab:
Threshold Tab:

As the script returns a numeric value 0 if the filesystem is not mounted, then the threshold will alert if the value is 0.

Assignment Tab

Assign to the custom alert created earlier.

Add Variants

The variable passed to the saphostctrl operation is “FILESYSTEM”. We can add the rest of the filesystems as individual variants. The format for the operation parameters is as follows:


For example:

You can enter as many filesystems as you like as separate variants.

Activate Alert

Go to the “Metrics, Events, Alerts Hierarchy” tab, and activate System Monitoring.

Testing the Metric

In a non-Production environment, try to unmount a filesystem, and at most 5 minutes later, there should be an alert produced.

Author: Tony Swietochowski

SAP Basis Consultant with over 20 years experience. Currently leading the SAP Monitoring and Solution Manager as a Service (SMaaMS) operations in DXC Technology, based in Sydney, Australia.

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