Metricbeat: "system.filesystem.used.pct" is not correct


I have the issue mentioned in the title.

I am using the following stack:

  • Version: 6.8.1 (same behavior in 6.7.1)
  • Operating System:
> cat /proc/version`
Linux version 4.4.0-142-generic (buildd@lgw01-amd64-033) (gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.10) ) #168-Ubuntu SMP Wed Jan 16 21:00:45 UTC 2019

Metricbeat Config Snippet using Elasticsearch output method:

- module: system
  - filesystem
  - memory
  - process
  - socket_summary
  enabled: true
  period: 5s

Metricbeat submits the following information:

On the host itself df delivers the following information:

The numbers reported by metricbeat are wrong for all filesystem partitions. The case above is just one example.

Any explanation as to why this is happening?

Maybe a little bit more background information about the partition table of the host filesystem:
