When formatting a hard drive, SSD, USB drive or memory card, you need to choose a file system. A very important choice because it determines the use and compatibility of your storage device…
USB key, memory card, hard drive, SSD: whatever its nature, and regardless of its capacity, a storage medium must be “formatted” – ie prepared to accommodate files – in order to be used. In principle, all storage devices sold on the market are already formatted at the factory by their manufacturer, and therefore ready for use. But it is common to have to reformat a medium, whether to delete all its content or to use it on different devices (PC under Windows, PC under Linux, Mac, television, Internet box, audio-video player, NAS , etc.).
If the operation itself – formatting – is not complicated, it imposes to choose a “file system”. However, this famous system is very important, because it determines the way the files are organized on the medium, but also, and above all, the operating systems – and therefore the devices – which will be able to access them. And it is precisely the choice of this file system that poses a problem for the uninitiated when it is necessary to configure the formatting. So here’s what to know if you need to format a storage device, whether it’s a hard drive, SSD, USB drive, or flash memory card.
What is a file system?
Regardless of the technology it employs (magnetic on hard drives, optical on CDs, DVDs, and Blu-rays, or electronic on SSDs, USB drives, and memory cards), a “permanent” storage device ” is characterized first of all by its recording capacity – its “size” -, most often expressed in gigabytes (GB) or terabytes (TB), knowing that 1 TB corresponds to 1000 GB and that 1 GB corresponds to 1000 MB (megabytes) since the standardization of the measurement system in 1998. It is this capacity that determines the size and the number of files that the medium can accommodate and keep, even in the absence of a power supply: it is the This is why we talk about permanent storage, as opposed to random access memory (Ram, in English) which is volatile in nature and loses its content as soon as it is no longer powered.
To organize the files it contains, a storage device uses a file system. Clearly, a way to “store” the digital data entrusted to it. To take an image, imagine a storage medium like a warehouse, initially empty. To store objects there, it is necessary to place shelves there and to opt for a storage method with references allowing to locate the locations. This organization is called the file system.
The difficulty comes from the fact that there is not one, but several file systems, each with its specificities, and therefore its advantages and disadvantages, but all decked out with cryptic acronyms (FAT32, NTFS, ExFAT, HFS+, ext3 …). The older ones were designed for low capacity media and old operating systems, which allows them to be widely recognized. Others, more “modern”, are better suited to devices and large files, but they are reserved for recent operating systems and devices. Windows thus has its privileged file system, the NTFS, whereas macOS has long preferred HFS+ and that removable media and multimedia devices use FAT32 or ExFAT instead… The question of compatibility is therefore essential when choosing a file system, a choice that is made during formatting, when preparing the substrate.
To use the analogy of the shed, formatting is similar to the layout of the warehouse: depending on the system chosen, there are more or less high shelves, more or less deep, more or less distant, etc. And to continue with this image, you should know that a storage device, such as a warehouse, can be subdivided into several “independent” parts: this is called partitioning. In fact, rather than using all the space in one piece, it is sometimes useful to create “rooms” separated by partitions, each with its own storage system: one with small shelves and small aisles for store small items, another with large shelves and wide aisles for bulkier items, etc. The same goes for a disk or an SSD, which can be subdivided into several independent subsets called volumes or drives, each with its own file system. It is also possible on a USB key or memory card, although this is generally less interesting.
Still, it is always a volume or a drive that is formatted, which assumes that the storage device has at least one partition – a “room” that can be converted. Nothing prevents you from creating several partitions – therefore several volumes or drives – on a single storage device – as long as it has sufficient storage capacity – and choosing a different file system for each one. Each partition will appear as an independent volume or drive on the device, even though they are all physically on the same medium.
Finally, let us note that the choice of a file system influences the real capacity of a medium, just as the layout of a room influences its usable volume: in the same way that a cupboard with multiple drawers leaves less space than a large shelving unit, the actual capacity of a formatted storage medium is always less than its raw capacity. This is the reason why the capacity indicated by a memory card, USB stick or disk is never fully available for data storage. That’s why a 256 GB SSD, for example, only offers about 238 GB of free space depending on the chosen file system.
Which file system to choose for formatting?
Not all devices can read and write all file systems! It is therefore necessary to choose the right file system when formatting, especially for removable media that you pass from one device to another – USB sticks, USB external drives, microSD memory cards.
- FAT: this very old format can only be used on low capacity storage devices, maximum 2 GB. It is found on old USB keys or memory cards, often formatted in FAT. Beyond 2 GB, FAT32 and exFAT have taken over.
- FAT32: although aging, it is the most universal format, especially for removable media. It can be read and written by PCs, Macs, Linux, digital cameras, TVs, game consoles, Internet boxes, smartphones… Main restrictions: a file cannot exceed 4 GB, which is constraining to create or read large videos in high definition, and the partition on the disk cannot exceed 2 TB. Prefer ExFAT when possible.
- NTFS: Microsoft’s favorite format for PCs. Choose this format for the internal drives of your PCs running Windows 7, 8 or 10. But only adopt NTFS on your small external USB drives and other removable media if you are sure you are only plugging them into PCs running Windows (or Linux). On a Mac, for example, only reading NTFS partitions is allowed, not writing (at least not without the addition of special apps). And removable NTFS storages are not always read by TVs, consoles and media devices.
- ExFAT: under the impulse of Microsoft, this format is intended to replace FAT32, of which it removes the limits. It was designed for removable storage like USB sticks and small memory cards. It can be read and written by Windows, macOS and Linux, and is also recognized and correctly handled by recent multimedia devices, such as the Playstation 4 and Xbox One (but not the PS3 or Xbox 360, for example). Older devices don’t always recognize it. If a device accepts both formats, prefer exFAT formatting rather than FAT32.
- APFS and HFS+: Apple File System (APFS) is the latest evolution of Apple’s file system. Designed in particular to manage SSD drives more efficiently, it equips the latest versions of macOS, iOS and tvOS (Apple TV), and succeeds the HFS+ file system. These file systems are preferred with macOS, on the internal disks of Macs and external USB disks that you will only use on Mac, for automatic backups, for example. These formats that cannot be read by Windows (without the addition of paid software) are rarely recognized by consumer electronic devices.
- ext2, ext3, ext4: the main GNU/Linux file systems, not immediately recognized by Windows and macOS. Linux ext2/3/4 partitions are, however, readable or read/write by installing free or paid software for Windows or macOS.
As we said, a file system corresponds to a certain organization of a storage device – more precisely, volume or drive. And if it is incompatible with a device, it must be changed.
The most natural technique is to reformat the media to choose another file system. The downside is that this method involves losing everything the device contains, which is not always the goal…
Fortunately, there are ways to modify the file system used on a disk or a key without reformatting and therefore without losing data. To do this, you need to use specialized tools, such as AOMEI Partition Assistant Standard or Macrorit NTFS to FAT32 converter, which are freeware, or Diskpart, a utility built into Windows, which are able to change the file system without erasing the data present. . Be careful, however, because the operation is sensitive, and there is a risk of data loss. The wisest thing is to back up the contents of a medium before reformatting it.