Diagnosing Disk Space Issues on Linux with df and du Commands

While publishing a test service via a web release platform, one of two nodes failed to start, causing TPS to stay low; log inspection revealed an "IO" error indicating the disk was full.

Check overall disk space: use the command

df -h

to display free space on all mounted filesystems.

View usage per subdirectory: run

du --max-depth=1 -h

(default path is the current directory). The

-h

flag makes sizes human‑readable (K, M, G). The output lists each subdirectory’s size and a total line.

Get the size of a specific directory: use

du -sh

. This prints a summarized, human‑readable size for the current directory.

Alternative command:

du --max-depth=0 -h

produces the same result as

-s

, showing only the total size.

You can also specify a path, e.g.,

du -sh /root/sw

, to check the size of a particular directory.