Inodes and 'No space left on device'

How to see it

'df -i' lists total, used and free inodes per file system. 'ls -i' shows a file's inode number, and 'stat <file>' shows its inode details.

Typical causes

Session or cache directories of web applications, mail queues, unrotated small log files and build caches can create millions of files.

Finding the directory

GNU du can count inodes: 'du --inodes -x / | sort -n | tail' lists the directories with the most entries.

How to fix inode exhaustion

1. Confirm: df -i (IUse% near 100%).
2. Find the directory: sudo du --inodes -x --max-depth=3 / | sort -n | tail -20
3. Check what creates the files before deleting anything.
4. Remove old files of that application with its own tool, or with find, for example: find /path -type f -mtime +7 -delete after a dry run without -delete.

Cautions

• Always run find without -delete first and read the list.
• The inode count of ext4 is fixed when the file system is created.

Sources

• inode(7)
• df(1)
• du(1)
• find(1)