Werk #20153: df: Fix crash when a filesystem's usable capacity is 0

Component

Checks & agents

Title

df: Fix crash when a filesystem's usable capacity is 0

Date

Jul 6, 2026

Level

Trivial Change

Class

Bug Fix

Compatibility

Compatible - no manual interaction needed

Checkmk versions & editions

3.0.0b1 Not yet released	Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.5.0p9 Not yet released	Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.4.0p34 Not yet released	Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

The filesystem check (df) and other checks that reuse its logic — Pure Storage FlashArray capacity/volumes and sansymphony pool — could crash with ZeroDivisionError: float division by zero when the reported usable capacity was zero, for example when a filesystem had its entire capacity reserved for the root user. These checks now report a WARN status with the following summary: "Size of usable filesystem is 0 B"

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