FAT: Explanation & Insights

A popular file system for USB sticks

FAT (File Allocation Table) is a filesystem that was initially designed for use on floppy disks and later adopted for hard disks. It's one of the simplest and most widely recognized file systems making it ideal for interoperability between different systems. It's important to understand FAT as it's widely used in removable storage devices like USB flash drives, SD cards, and is also used in embedded systems due to its simplicity.

How Does FAT Work?

The term "File Allocation Table" comes from the use of a table that keeps track of which parts of the disk are used by which files. When a file is to be read, the kernel looks up the first part of the file, then follows the links in the table until the entire file has been read.

Why is FAT Important?

FAT is crucial for data exchange between different operating systems. Since it's recognized by nearly all existing operating systems, a USB drive formatted with FAT can be read by Linux, Windows, macOS, and many others. This makes FAT a universal exchange format.

Common FAT Problems

There are a few common issues that can occur with FAT file systems. These include problems such as file fragmentation, size limitations, and lack of support for file permissions.

Using FAT on Linux

On Linux, you can use several commands to interact with FAT file systems. The mount and umount commands are used to mount and unmount FAT file systems respectively. The mkfs.vfat command can be used to create a FAT filesystem.

For example, to create a FAT32 filesystem on a device located at /dev/sdb1, you would use the following command:

mkfs.vfat -F 32 /dev/sdb1

FAT vs other File Systems

While FAT is great for compatibility, it lacks many features provided by more modern file systems. For example, compared to NTFS, exFAT, or ext4, FAT doesn't support file permissions, hard links, or files larger than 4GB (in FAT32). It's also more prone to fragmentation.

Therefore, while FAT is often a safe choice for removable media, for your Linux server, you might want to use a file system like ext4 or XFS, which offer more robust features suitable for a server environment.


While FAT might not be the most powerful or feature-rich file system, it's wide compatibility makes it an essential part of any Linux user's toolkit. Understanding how it works and how to work with it on Linux is a valuable skill for any aspiring Linux server administrator.

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