How to Quickly Identify Disk Space Hogs on Linux Servers

During server operations you may receive disk‑space alerts. Use df -Hl to view the current usage.

How to locate large directories or files

A simple way is to run du -hs in the root directory and then drill down into the reported directories.

A more efficient method adds the -d or --max-depth option to limit depth, piping the output through grep to filter and sort the results, which quickly reveals directories measured in G or T.

You can also use find to search for big files, for example: find / -type f -size +1G -exec du -h {} \; In terms of speed, find is generally faster and more flexible than du.

Dealing with hidden space consumption

Sometimes the sum of sizes reported by du is far less than the usage shown by df. This often means deleted files are still holding space.

Use lsof +L1 to list open files that have been deleted. An example output may show a ~28 GB log file that is deleted but still occupies space. lsof +L1 Restarting the affected application (e.g., Tomcat) releases the space.

Why used space may appear larger than expected

Linux reserves a percentage of disk space (default 5 %) for the root user as a safety buffer, which can make Used + Avail < Size.

You can adjust this reserved space with tune2fs: tune2fs -m 1 /dev/vda1 After reducing the reserved percentage, the previously “missing” space becomes available.