The new update to the ageing HFS+ file system will bring higher performance, better data integrity, and a vastly improved Time Machine.
Don’t worry it is not a step into the unknown APFS is already running on your iOS device (ipad,iphone etc).
When and if you upgrade your system to High Sierra (macOS 10.13), it will automatically during installation upgrade the file system to APFS on the system drive, the internal drive usually named Macintosh HD.
External drives and non system drives must be upgraded manually, via Disk Utility. Select the volume to be upgraded, left click, and the contextual menu has a Convert to APFS option.
Using FileVault? macOS will automagically convert it to APFS without decrypting your data. Your passwords and recovery keys will be preserved in the process.
The file system scales from an Apple Watch to a Mac Pro. It uses 64-bit inode numbers, and allows for more secure storage. The APFS code, like the now 19 year old HFS+ code, uses the TRIM command for better space management and performance.
Clones allow the operating system to make efficient file copies on the same volume without occupying additional storage space. Changes to a cloned file are saved as deltas, reducing storage space required for document revisions and copies. More on Delta encoding can be read here: https://en.wikipedia.org/wiki/Delta_encoding
Apple File System snapshots a point-in-time, read-only instance of the file system. Rather like windows restore points, one of the better features of Windows and handy as it’s not as reliable as our beloved macOS, Snapshots are similar to clones, in that they preserve the state of the file system at a particular moment. APFS logs all the references and metadata and, using Copy On Write (COW), only writes newly changed blocks after the snapshot. Snapshots use less space than a complete copy would.
Time Machine is much improved with APFS’s snapshot capability, the TM software is much simpler and faster.No more slowing Mac while it completes a backup!
Apple File System natively supports full disk encryption, and file encryption with the following options:
Apple File System is designed to prevent metadata corruption caused by system crashes. Instead of overwriting existing metadata records in place, it writes entirely new records, points to the new ones and then releases the old ones. We’ve only really just scratched the surface here with the new file system for Macs , it promises to be a big update in terms of performance of macOS itself.