It is a replacement for the existing HFS+ filesystem which Apple has used since 1998 for its devices. If you are an Apple user, as you upgrade to iOS 10.3, tvOS 10.2, watchOS 3.2, or MacOS High Sierra (coming this Fall), your device will be automatically updated to the new APFS.
Why does this matter to you?
- This is an important step towards streamlining the experience on all Apple devices. Laptops, desktops, phones, watches, TV devices, and whatever else Apple releases in the “undiscovered country” of the future will use the same underlying filesystem. As Apple increasingly merges the experiences of the iOS and MacOS-based devices, sharing the same filesystem will help in this endeavor.
- This filesystem is optimized for flash and solid-state storage devices. When HFS+ was released in 1998, spinning magnetic media (e.g. floppy disks and spinning hard drives) were the normal means of storing data. Now, however, these have largely been replaced by SSD and flash storage, particularly in Apple devices. With a new filesystem optimized for these devices, Apple can increase performance with regards to speed, storage capacity, and data integrity.
- Native encryption is supported. APFS supports full disk encryption, no encryption, and two levels of file-based encryption. This ensures the security of the data on the device so that non-authorized persons cannot gain access, even if they have the physical device.
- Ability to address up to 9 quintillion files in a single filesystem. This is owing to the fact that APFS uses 64-bit inode numbers. An inode is basically a logical pointer to a file; each file requires one inode number. The previous HFS+ filesystem used 32-bit inode numbers, allowing for “only” approximately 4.3 billion files. The improvement for APFS will really be seen in server environments where large numbers of files are stored.
- The existing HFS+ filesystem can only handle dates up to February 6, 2040. Does that seem like a long way away? Well, it’s only 23 years in the future, and we’re 19 years removed from the introduction of HFS+.
There are other under-the-hood improvements with APFS. The main takeaway, however, is that going-forward APFS will be used on Apple’s devices and will make better use of SSD and flash storage. You shouldn’t have to worry or even know about the change; as you update your devices to the latest versions of the Apple’s operating systems you’ll get the new filesystem automatically, along with the benefits it provides.