Disk Usage Analysis with df, du, and ncdu

Tutorial Overview

Learn to analyze and manage disk space usage using df, du, and ncdu on Debian-based systems. These tools help identify storage usage trends and allow efficient disk space management.

Prerequisites

• Root or sudo access.

Steps

Step 1: Check Disk Space Usage with df

1. Run df to view available and used disk space:

df -h

• The -h option displays output in a human-readable format (e.g., MB, GB).
• Important columns:
  • Filesystem: The name of the disk or partition.
  • Size: Total size of the filesystem.
  • Used: Space currently in use.
  • Avail: Available space.
  • Use%: Percentage of space used.

2. Focus on Specific Filesystems:

• To display only specific filesystems, use:

df -hT /path/to/mountpoint

Step 2: Find Disk Usage by Directory with du

1. Use du to show the size of a specific directory:

sudo du -sh /path/to/directory

• The -s option gives a summary, and -h makes the output human-readable.

2. Display Sizes of All Subdirectories:

• To list all subdirectories within a directory, use:

sudo du -h --max-depth=1 /path/to/directory

• Adjust –max-depth to control the level of detail.

3. Identify Large Files Recursively:

• Find large files by sorting du output:

sudo du -ah /path/to/directory | sort -rh | head -n 10

Step 3: Use ncdu for a Visual Disk Usage Summary

1. Install ncdu:

sudo apt install ncdu -y

2. Run ncdu in the desired directory:

sudo ncdu /path/to/directory

• ncdu provides an interactive display of directory sizes, making it easy to identify large files and folders.

3. Navigating ncdu:

• Use the arrow keys to navigate.
• Press Enter to explore a directory.
• Press d to delete a selected file or directory.
• Press q to quit.