You don’t have to do anything special to switch your Mac to the new APFS file system. RELATED: What's New in macOS 10.13 High Sierra, Available Now Apple File System, also known as APFS, has been used by default on iPhones and iPads since iOS 10.3, and is also used on the Apple Watch and Apple TV-but now it’s finally on the Mac, too.
Apple’s macOS 10.13 High Sierra brings a new file system named “Apple File System”, which largely replaces the older HFS+ file system.