What is an inode?
By Ash, Founder, HosteazePublished 2 min read
The short answer
An inode is the record a Linux server keeps for every file and folder, holding details like its size, owner and where its data sits on disk. Every file uses one, however small. Shared hosting plans often cap the number of inodes, so lots of tiny files can hit the limit before disk space runs out.
Imagine a library's card catalogue. The books are your files, and every one of them has an index card saying what it is, who owns it and which shelf it's on. On a Linux server, those cards are called inodes, short for index nodes. A 2 KB thumbnail and a 2 GB video each get exactly one.
What does an inode store?
According to the Linux kernel documentation, the inode holds a file's metadata: timestamps, the map of where its data blocks are, permissions and other attributes. Oddly, it doesn't store the file's name. That lives in the folder, which points to the inode.
For hosting purposes, the takeaway is simpler. One file or folder equals one inode, so the count tracks the number of things, not their size.
Why do hosting plans limit inodes?
Every inode takes a little memory and work to manage, and millions of tiny files make backups, malware scans and file system checks slow for everyone sharing a server. So many shared hosts set an inode limit alongside disk space. The figure varies widely by host and plan, so check yours before you assume it's unlimited.
What uses up inodes on a website?
| Culprit | Why it adds up | Fix |
|---|---|---|
| Cache plugins | Can store a separate file for every page, sometimes per device | Clear the cache and set a sensible expiry |
| Old email | Every message is a file in most mail setups | Archive or delete old mail, empty the trash |
| Image thumbnails | WordPress creates several sizes of each upload | Remove unused image sizes, delete unused media |
| Old backups and staging copies | A full copy of your site doubles the count | Download them, then delete them from the server |
| Session or log files | Can pile up silently over years | Ask your host or developer to rotate them |
How do I check and reduce my inode usage?
- Look in your control panel for a figure labelled inodes, file usage or file count.
- If you have SSH access, run
du --inodes -d 1 ~ | sort -nto see which folders hold the most files. - Clear your caching plugin's cache and check its settings.
- Tidy old email, starting with folders like Sent and Trash.
- Delete old backup files and abandoned site copies from the server once you have a copy elsewhere.
If you keep bumping into the limit after a tidy-up, your site may simply have outgrown its plan. Our guide on how much storage your website needs helps you size the next step, and what web hosting is covers the basics.
More plain-English guides are in Email and domains.
Frequently asked questions
What happens when I hit my inode limit?
The server refuses to create new files. Uploads fail, plugins can't update, caches stop writing and, on many setups, new email can't be delivered to your mailbox. Your site may keep running but start behaving strangely.
Do emails count towards my inode limit?
Usually, yes. Most mail servers store mail in a format called Maildir, where each email is its own file. A mailbox with 40,000 old messages uses about 40,000 inodes on its own.
Does deleting files free up inodes straight away?
Yes, once the file is actually deleted. Files moved to a trash or recycle folder in your control panel or email client still count until that folder is emptied.