Scenario:

Your server cannot create new files. Commands like touch fail with "No space left on device" errors, but df -h shows plenty of free disk space. The filesystem has exhausted available inodes.

Task:

Save inode usage to /home/interview/inode_usage.txt, find which directory contains excessive files, save the problematic directory path to /home/interview/problem_directory.txt, clean up the files, and verify the fix.

Example

File: /home/interview/inode_usage.txt

Filesystem            Inodes   IUsed   IFree IUse% Mounted on
/dev/sda1            6553600 6553600       0  100% /
/dev/sdb1            3276800  125000 3151800    4% /data

File: /home/interview/problem_directory.txt

/var/spool/postfix/maildrop

Step 1: Check inode usage

df -i

If df -i shows 100% IUse% on a filesystem, inodes are exhausted. Inodes are file system data structures that store file metadata; each file consumes exactly one inode, regardless of its size.

Step 2: Save inode usage to a file

df -i > /home/interview/inode_usage.txt

Step 3: Find the directory consuming the most inodes

du --inodes --max-depth=1 / 2>/dev/null | sort -n

The --max-depth=1 limits scan to immediate subdirectories, sort -n puts highest usage at bottom, and 2>/dev/null suppresses permission errors.

Step 4: Drill down into the high-usage directory

du --inodes --max-depth=1 /var 2>/dev/null | sort -n

Replace /var with the directory from Step 4. Continue drilling down (e.g., /var/spool) until you find the specific problematic subdirectory.

Step 5: Count files in the problematic directory

find /var/spool/postfix/maildrop -type f | wc -l

Replace with your actual problematic directory path.

Step 6: Save the problematic directory path

echo "/var/spool/postfix/maildrop" > /home/interview/problem_directory.txt

Replace with your actual path.

Step 7: Examine the directory

ls -la /var/spool/postfix/maildrop | head -20
du -sh /var/spool/postfix/maildrop

Check file types and total size. Often many small files take little space but consume many inodes (common in /var/spool, /tmp, /var/cache).

Step 8: Clean up the files

sudo rm -rf /var/spool/postfix/maildrop/*

WARNING: Only delete if you're certain these files are safe to remove!