Computer File Systems Explained

My guess is that you are here because you are either completely and utterly bored or you are extremely inquisitive. Okay, add the list obsessive compulsive. File systems aren’t something that most people want to know about unless they love learning about technology. But we can make this learning process much easier. It seems that for technology there is an endless line of technical people ready to make it even more complicated. Let’s not do that.

File systems are like, well, files. Remember those things? Files hold file folders, which in turn hold papers. This makes finding things easy, right? Well, the same holds true for file systems on a computer. It keeps files all nice and tidy. It’s our job to make it messy. Insert maniacal laugh. Let’s look at the different file systems in use on some popular operating systems.


Since Windows dominates the marketplace right now, let’s look at it. The “old” days saw DOS. Okay, nuff said. No really, I can’t pull myself to talk about Dos and how it was built off of QDOS, etc. Windows went on the the FAT system. That’s File Allocation System. At first there was plain old FAT, then FAT16, and finally FAT32. FAT and FAT16 had issues with long file names and hard drive sizes. FAT32 took care of some of those issues. Also, file security was basically non-existent in this type of file system. It was the hacker’s hayday. Throw netbios on top and boy, it was a regular square dance. But I digress. With the NT line of Windows operating systems, Microsoft introduced the NTFS file system. NTFS also has better support for longer file names, mount points, and file security. Ok, had enough? No you say – man you need to get some rest.

Mac OS X

Mac OS X utilizes the HFS file system. It supports file names up to 255 characters long, is metadata driven, and uses native defragmentation. It inherits Unix permission on the file system.


The most popular file system on linux is ext3. Ext3 is a journaling file system that allows for rollbacks. It has nice file security and easy administration. One of the big drawbacks is not inline defragmentation that is seamless.

I could go on and on about advantages and disadvantages of different file systems, but I won’t bore you. That’s the bird’s eye view. I hope it was helpful.