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File systems: what are they and which are the most important

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What is a files system?
Major file systems
Is it possible to change the file system?
FAT (File Allocation Table or file allocation table)
exFAT (Extended File Allocation Table or extended file allocation table)
NTFS (New Technology File System)
HFS + (Hierarchical File System)
APFS (Apple File System)
Summary of the most important file systems

File systems: what are they and which are the most important

File systems have been around for decades. The first punched cards and magnetic tapes already used them. However, these only allowed the information to be accessed sequentially: for example, finding the precise place where some data was stored on a reel of magnetic tape required a very slow reading process. Today, file systems allow data to be accessed randomly , exponentially speeding up the recovery process. If you're wondering what exactly a filesystem is and which ones exist, read on..

  1. What is a files system?
  2. Major file systems
    1. FAT (File Allocation Table or file allocation table)
    2. exFAT (Extended File Allocation Table or extended file allocation table)
    3. NTFS (New Technology File System)
    4. HFS + (Hierarchical File System)
    5. APFS (Apple File System)
    6. ext4
    7. Summary of the most important file systems
  3. Is it possible to change the file system?

What is a files system?

A file system is the storage system of a memory device , which structures and organizes the writing, searching, reading, storing, editing and deleting of files in a specific way. The main objective of this organization is that the user can identify the files without error and access them as quickly as possible . File systems also give files, among others, the following characteristics:

  • File naming conventions
  • File attributes
  • Access controls

Also, file systems are an important operational component, since they act as an interface between the operating system and all devices connected to the computer (internal and external, such as USB sticks).

To install a file system, the data medium must be formatted . The storage media that are sold are already formatted. In the past, it was common for the user himself to have to configure new data carriers to store and manage files..

Format options, including the file system selection for external data support (chiavetta USB, currently formatted in FAT) in Windows 10.

Major file systems

There are several standard file systems for Windows, macOS, Linux, Unix, and all other operating systems. In recent years, with the development of new technologies, they have become more and more differentiated: for example, suitable file systems have been created for the increasingly popular flash storage devices , including memories USB and SSD drives. All file systems share the characteristic of using a tree structure to organize files, starting from the root directory. From there, the rest of the folders or directories and subfolders branch.


Although they have some similarities, the file systems are in principle incompatible with each other . For example, if you connect a portable hard drive with APFS (short for Apple File System, released in 2017) to a Windows computer, it will not be recognized by the Windows computer. Nor are the file systems used in Linux automatically compatible with other operating systems. However, in general, third-party programs can always be used , which allow, for example, read and write access to incompatible data carriers..

Today, there are quite a few file systems, although not all are equally widespread . The most common to date are FAT16, FAT32, exFAT and NTFS (Windows) and HFS + and APFS (macOS / Mac OS X). Linux currently uses ext4 (successor to ext3 and ext2), among others. We briefly summarize the characteristics of these file systems below.

FAT (File Allocation Table or file allocation table)

This file system has been around since 1980. Versions released since then are called FAT12, FAT16, and FAT32. The FAT format is ideal for handling a small volume of data . From today's perspective, the FAT file system is outdated, because even in the most modern and powerful variant (FAT32, released in 1997), files can have a maximum size of 4 gigabytes (GB). FAT32 also limits the maximum partition size to 8 terabytes (TB).

Despite these limitations, the FAT format is still very common. It is used for removable portable data carriers (external hard drives or USB sticks) and special hardware (digital cameras, smartphones , routers, televisions, car radios, etc.). It has the widest range of compatibility, especially on mobile devices.

exFAT (Extended File Allocation Table or extended file allocation table)

This format, published in 2006, is the evolution of FAT, the classic format. exFAT was originally designed for removable storage media and, therefore, is particularly suitable for flash drives, memory cards and external hard drives, such as solid state drives (SSD, English acronym of solid-state drive ) with storage capacity individual. exFAT works particularly efficiently with smaller data carriers . However, it can also process large files and far exceeds the 4GB limit of FAT32. Since Windows 7, exFAT is natively supported (therefore it is the factory standard and does not entail the need to install additional drivers or special service packs).

NTFS (New Technology File System)

The NTFS file system, which was introduced in 1993 with the Windows NT operating system, has been the standard file system for Windows computers since Windows Vista. It offers several advantages over FAT, such as the ability to compress the storage media and greater data security (for example, through encryption). A special feature of NTFS is that the share and access rights of files and folders can be defined in detail and comprehensively. Users can assign local and remote access rights over the network.

HFS + (Hierarchical File System)

This file system, released in 1998, is an evolution of HFS for Apple. To clearly differentiate the two standards, there is also talk of Mac OS Extended (HFS +) and Mac OS Standard (HFS). Compared to HFS, HFS + works faster and more efficiently in handling, reading, and writing data. It also allows you to manage more files by supporting up to 4 billion blocks of files or folders. Linux can read and write data directly with HFS +, although special packages (hfsutils, hfsplus, hfsprogs) need to be installed in some cases. Windows requires additional software to fully support HFS +.

APFS (Apple File System)

APFS, launched by Apple in 2017, meets the requirements of modern solid state drives first and foremost . APFS is designed as a 64-bit system, allowing data and files to be encrypted. If an operating system is on an SSD, the HFS + file system is automatically converted to APFS. This? Automatic formatting? It was introduced with the High Sierra operating system. Since macOS 10.14 Mojave, Fusion drives (logical drives made up of SSDs and mechanical hard drives) are also migrated to APFS automatically. On certain occasions, problems may arise when converting from HFS + to APFS.


ext4 was introduced in 2008 as a successor to ext3. This file system is currently the standard for many Linux systems, such as Ubuntu. Its most important novelty is the extents function , which optimizes the handling of large files and prevents fragmentation more efficiently than its predecessors. With ext4, partitions can be made larger and smaller as needed, and even during processing. Unlike ext3, which supported a maximum of 32 terabytes, the ext4 file system supports a maximum volume many times greater, of 1 exabyte (approximately 1 million terabytes).

Summary of the most important file systems



Operating system (compatibility)



Removable storage media

- Windows

- Mac OS X / macOS

- Linux (if the corresponding drivers are installed)

- High compatibility

- Compatible with many types of hardware

- No encryption or compression features

- It does not particularly guarantee the security of the data

- Ideal for smaller partitions

- Maximum data volume: 4 GB


Removable storage media

- Windows

- Mac OS X / macOS (compatible as of 10.6.4)

- Linux (if the corresponding drivers are installed)

- Not yet a generalized standard

- Does not allow managing rights

- It does not allow to compress the data

- Ideal for smaller flash drives , starting at 32 GB (USB sticks, SD cards)

- Unlimited sizes and partitions (based on current state of technology)

- Maximum data volume: 512 TB


Internal and external hard drives

- Windows

- Mac OS X / macOS (comprehensively by installing additional software )

- Linux (installing drivers)

- Rights management

- Improved data security: protects against the loss and modification of data; allows encryption

- Allows you to compress the data;

high performance with large storage media

- Specializes in large files and large storage capacities

- Unsuitable for small disks and partitions under 400MB (too much power)

- Maximum data volume: 256 TB


SSD drives

- macOS (the standard since version 10.13 High Sierra)

- Older versions of Mac OS and Windows (installing additional software )

- Optimized for Solid State Drives (SSD) and other flash storage devices

- Also works on mechanical and hybrid units

- Allows data encryption

- Optimize storage space management (shared space feature)

- Freeze protection function, which protects against file system damage (for example, in case of system crash)

- Compatible with Fusion Drive from macOS 10.14 Mojave

- Maximum data volume: 8 exbibytes


Internal and external hard drives

Mac OS X / macOS

- Mature and tested file system

- Especially suitable for mechanical discs

- Not optimized for modern storage technologies (SSD, flash )

- Better backward compatibility than APFS

- Limited useful life; will probably no longer be supported by Apple in the long term

- Will gradually lose importance due to? Forced conversion? and partially automated to APFS

- Maximum data volume: 8 exbibytes



- Linux

- Windows (only with additional software )

- Mac OS X / macOS (only with additional software )

Compared to previous versions of ext:

- Performance improvement

- Improved data security

- Incorporates encryption (since Linux Kernel 4.1)

- New extents feature increases the processing speed of large files and prevents fragmentation

- Rights management

- Maximum data volume: 16 TB

Is it possible to change the file system?

The compatibility is very important when choosing the format, for example, if you want to use an external hard drive not only to your home computer, but also on other platforms and devices. For maximum flexibility to transfer data between an Apple and a Windows device, we recommend, for example, formatting the exFAT file system. In short, correctly formatting the storage media can be decisive, since it saves you complications and limitations when transferring data from one medium to another on a day-to-day basis.

If the basic requirements are met (for example, having up-to- date hardware ), you can also switch systems at any time and, for example, switch from an old file system to a more modern one . However, it is essential to check beforehand if there is no risk of losing the files or if all the data must be backed up first and then copied back to the storage medium. There are free and paid programs for this type of conversions, which allow them to be carried out more comfortably and safely. In some cases, however, it is also possible to format the file system using the resources provided by the operating system itself. In our article on formatting USB sticks you will learn, for example, how to convert the file system of a USB stick directly in Windows.