How to Quickly Identify Disk Space Hogs on Linux Servers

How to Find Large Directories or Files

When a server triggers a disk‑space alarm, start by checking the filesystem with df -Hl to confirm the reported usage.

To locate the offending directories, a straightforward approach is to run du -hs in the root directory and then repeat the command in sub‑directories.

A more efficient method uses du with the -d or --max-depth option together with grep to filter and sort results, allowing you to quickly spot directories that occupy gigabytes or terabytes.

Alternatively, the find command can directly search for large files, e.g.: find / -type f -size +1G -exec du -h {} \; In practice, find is often faster and more flexible than du.

Sometimes the sum of sizes reported by du does not match df because deleted files are still held open. Use lsof +L1 to list such files; restarting the related service (e.g., Tomcat) releases the space. lsof +L1 Linux also reserves a percentage of disk space for the root user (default 5%). This reservation can be changed with tune2fs -m 1 /dev/vda1, which reduces the reserved space to 1% and frees up the previously hidden capacity.

tune2fs -m 1 /dev/vda1