CertGrid CertGrid
Hands-on Lab·CompTIA Linux+

Storage faults: full, out of inodes, and busy

Three storage faults are built on purpose on a 32 MB loop filesystem, so nothing on the host is at risk. A disk that fills, a disk with plenty of space and no inodes left, and a mount that refuses to unmount - each with the command that names the cause, and one where df and du disagree by 26 megabytes and both are right.

Troubleshooting Guide 25 of 28 Intermediate

One host. Every fault is built on a 32 MB file mounted through a loop device, so the machine's own storage is never involved.
Server NameIP AddressOSRolesCPURAMHDD
LPLUS-A01192.168.0.73Ubuntu 26.04 LTSDebian-family host - apt, ufw, netplan, AppArmor2 Core4 GB50 GB

This guide includes

Use this when a machine reports it is out of space, or a filesystem will not unmount during a maintenance window. This matters because the same error message covers two unrelated causes, and because deleting the big file does not always give the space back.

Before you start

  1. A small filesystem to break on purpose

  2. Fault one: no space left

  3. The space df can see and du cannot find

  4. Fault two: no space left, with the space still there

  5. Fault three: a mount that will not unmount

  6. Putting the machine back

Official sources

← All Linux+ guides