What is an iNode?

Watch out watch out there's an iNode about!

That's the first question I had to ask myself when these little beasts started to cause me problems.

In computing, an iNode is a data structure on a traditional Unix-style file system such as UFS. An inode stores basic information about a regular file, directory, or other file system object, each iNode has an inumber, which is the identification number of the inode. So, whenever you create a file or a folder you're actually creating an iNode. And it doesn't matter if it's a teeny weeny little file, it's still an iNode.

Why are they called iNodes?

Jargon. Pure and simple. Why call it a file of a folder when you can call it something only those "in the know" will understand?

The exact reason for designating these as "i" nodes is unknown. According to Unix pioneer Dennis Ritchie:-

In truth, I don't know either. It was just a term that we started to use. "Index" is my best guess, because of the slightly unusual file system structure that stored the access information of files as a flat array on the disk, with all the hierarchical directory information living aside from this. Thus the i-number is an index in this array, the i-node is the selected element of the array. (The "i-" notation was used in the 1st edition manual; its hyphen was gradually dropped.)

Why should you be worried about iNodes?

If you're running a pretty standard website, or you have your own dedicated server (lucky you) you probably won't have to worry. But if you're using a host along with a CMS solution like Joomla or Drupal, or a Wiki, then start worrying.

Why worry? Simply because it is possible to "run out" of inodes. When this happens, new files cannot be created on the device, even though there may be free space available.

Not only that but your provider (in my case Siteground) will offer you all sorts of goodies, in my case it was:-

  • FREE domain name / 750 GB web space / 7500 GB traffic / 99.9% server uptime etc. etc. all for $5.95 a month!

What they don't mention (and I haven't found one that does) is that you're only allowed 150000 iNodes. Now this may sound like a lot, but just consider this, installing Joomla will use 50000 of them. It might take a while, but eventually you'll find that you've run out of iNodes, especially if you have a cache file, or mail account, or even allow comments. Eventually when you ask for help they'll probably try to sell you a dedicated server. The cost? $99 a month! Not such a bargain.

So, before you sign up for any hosting package ask about file / folder / iNode restrictions and any possibility to increase them.

About the author:

Lynne Hand runs several websites and basically learns as she goes.