File System Basics: What It Actually Means and Why You Should Care

You probably won’t be surprised by the fact that any storage device like a hard disk drive or memory card cannot be used without being previously formatted: Only then it will be recognized by the operating system and files can be written to the storage and then quickly retrieved when needed. But do you actually know that this process essentially involves setting up a file system and that there is not just one but a huge variety of them?

Though most users are not even aware of its existence, a file system is always there silently doing its vital job: all of your devices that need to store information in the digital form simply can’t function without it. But the thing is that most file systems are not equal, so even ordinary computer users need to give some thought to this matter.


The concept of a file system was born in the early digital era, back when computers cost the earth and made plain folks just go “wow”. However, at that time it was considered just a part of the operating system which powered those spooky room-sized machines. One of the earliest file systems, the lucky one to receive its own name, was DECtape, called after Digital Equipment Corporation (DEC), the company which introduced it in 1964. DECtape used to control a series of DEC’s minicomputers (don’t be misled by the word “mini”, they were actually about the size of your fridge), which stored data on giant whirring tapes that were extremely slow and able to hold 184 kilobytes each.

Nevertheless, like in the early days of computing, file systems are still associated with certain operating systems, probably because of the fact that some environments have a single file system option, but it is important to remember that the file system, in spite of being related, is fully separate from the OS. Moreover, the word itself has multiple meanings, and you may hear people confusingly talking of the file system as that directory structure starting from the root folder you can browse through using any file manager like File Explorer. That is why you should mind that the file system (in the sense we use the term) is hidden from the user and simply can’t be accessed with any standard tools. Still, when formatting a drive, you can choose which file system is to be applied.


To fully understand what a file system is just imagine a huge pile of books. All of them may have different authors, refer to different genres, vary in the number of pages and years of publication. In order to find the one you need and read it, you will have to dig through this pile the whole day long and may still be found wanting, unless these books are put on the shelves and organized according to some rules like in the library catalog. This is likely to kill your desire to read for a long time, even if you’re the most avid bookworm. Correspondingly, data on the hard drive or any other storage medium, whether it is just plain text, a digital photo or an app, is stored in the form of files, and the problem is how to arrange those files so that they could be easily found, updated or deleted.

When we format a disk, we make it organized by giving it a certain file system, which serves as a sort of digital index: it keeps track of all data and shares this information with the operating system. Apart from the contents of your files, it stores various metadata like their names, sizes, locations, when they were created or modified as well as some other additional parameters such as who has the right to access certain files. But for the file system, you would be left with a vast messy heap of worthless data instead of that dear-to-heart photo collection residing on your USB stick.


As nowadays we have a great many electronic devices that store our data of various kinds, to best suit specific needs a great many file systems have been developed. We can divide them into two categories: file systems used by all local storage devices, including internal and external HDDs, USB flash drives, memory cards and NAS boxes, and file systems that are deployed on server machines. The first category incorporates such file systems as FAT, exFAT, NTFS, HFS+, UFS, APFS, EXT2, EXT3, EXT4, XFS, ReiserFS, JFS. These are the ones you should know about and are likely to encounter as an ordinary home user. In contrast to “local” file systems, “server” ones, like ReFS, ZFS, Btrfs, NWFS and NSS are typically used in a professional setting by system administrators and other technical staff.


What is more, your operating system needs to understand the file system so it could communicate with it efficiently e.g. see its contents, modify them, write new files to it, etc. Hence, most modern file systems are OS-specific. For instance, for Windows you have NTFS and FAT, for Apple’s Macs and iOS devices you have HFS+ and the recently introduced APFS file system, whereas Linux supports a set of file systems such as ext, XFS, JFS and ReiserFS.


Still and all, there’s no single best file system for all uses. Some of them are speedier, some provide improved security features or resistance to data corruption, some support only drives with small capacity such as memory cards or USB sticks, while some can handle just colossal amounts of data. Therefore, knowing at least basic information about each of them will help you to choose the right one and make your computing experience much better preventing any trouble.

Follow our series of articles devoted to file systems to know a thing or two about the most common ones.

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