Apple has released High Sierra, a new upgrade to macOS that’s installable on most Macs built since 2009 and 2010. One of the key features of High Sierra is a new file system. There’s a hitch if you’re using a Mac with a hard drive, including Macs with Fusion Drives. File systems aren’t a sexy feature or even a visible one, but the last time the Mac’s file system changed, Bill Clinton was president. So it’s a big deal. Read on for the full story.