In what cases can the inode limit be exhausted in a file system?

An inode limit exhaustion in a file system occurs when the number of available inodes used to store metadata for files and directories runs out.

Main reasons:

• A very large number of small files. For example, if a system creates a huge number of small files (logs, temporary files, cache), the inode count can run out even if there is free disk space.
• Creating a large number of empty files or directories. Each file and directory consumes one inode.
• Using file systems with a fixed number of inodes. For example, ext3/ext4 create inodes at formatting, and their number is fixed.

Example: if thousands of temporary files are actively created in a loop on a server but not deleted, you may encounter the "No space left on device" error due to inode exhaustion, even though there is still disk space.

To check inode usage, use the command:

df -i

To resolve the issue, delete unnecessary files or recreate the file system with a larger number of inodes.