High Sierra, APFS, and your hard drive-equipped Mac

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.

Macbook highsierra file system

What’s APFS?

All computing devices rely on a file system to control how your device stores and retrieves data. The file system Apple has used on its device up until recently was called HFS Plus. HFS Plus was introduced in 1998, updating an earlier file system (plain old HFS) that had already been around for 13 years. So the Mac – and by extension, the iPhone, iPad, iPod touch and other Apple devices – used a file system that was 30 years old.

Times change, and so does technology – rapidly. Storage needs have increased exponentially HFS  debuted in 1985. At the time HFS was first introduced, a 20 MB hard drive was astonishingly big. Now devices in your pocket can hold 128 GB or more.

What’s more, there’s been a sea change in how storage works. When HFS Plus was introduced floppy disks and spinning hard drives were the way most devices stored data. Floppy disks are a historical relic, and hard drives are headed that way too. Now devices across Apple’s product like rely on flash storage – writing data to silicon instead of to the surface of a spinning disk.

Apple needed to future-proof its core file system technology, and needed to adapt it to the changing needs of flash storage. APFS was the solution. APFS employs advanced data integrity features to make sure your data is safe. It’s also tremendously more efficient when it comes to copying files and folders – you’ll see almost instant operations.

APFS is very much an “under the hood” change. You won’t notice anything visibly different, but the way in which your Mac stores files and interacts with its storage system are more efficient and better suited for the future than how it’s worked up until now.

APFS was rolled out to iPhone and iPad users earlier this year with the release of iOS 10.3. With the general release of High Sierra for the Mac, APFS has come to Macs too.

Auto-Conversion to APFS for Flash-Only Macs

If you’re using a Mac equipped with all-flash storage – a Retina MacBook Pro, for example, or a MacBook Air, MacBook, a 2013 or later MacBook, some Mac mini and iMac models – the conversion to APFS will be automatic when you first install High Sierra. The conversion to APFS even happens if you’ve upgraded your Mac with some Solid State Drives (SSDs). I put a third-party SSD in my Mac mini, and High Sierra’s installer managed the conversion to APFS without complaint.

If you’re using a Mac with a spinning hard drive, or Apple’s “Fusion Drive” equipped models, High Sierra will not automatically convert your device to APFS. Apple decided before High Sierra’s release to automatically convert only those Macs powered by pure flash storage. In fact, beta testers who have made the conversion on their hard drive-equipped Macs are required to reformat them to HFS Plus to install the general release.

APFS Coming Soon for Everyone Else

Apple has also said, unequivocally, that APFS will be coming to hard drive-equipped Macs in a future High Sierra update. In announcing High Sierra’s release, Apple said, “APFS currently supports every Mac with all‑flash internal storage — support for Fusion and HDD Mac systems will be available in a future update.”

Apple hasn’t explained the delay. I’ve heard through the grapevine that a certain number of hard drive-equipped Macs were failing the installer’s initial conversion. If that’s the case, Apple’s decision to delay APFS conversion for those Macs is prudent. No one wants to install software that could potentially leave our Mac as a doorstop.

As always, having a backup and recovery strategy is important. Flash-equipped or not, make sure your Mac is backed up. For more on prepping your Mac for the switch to High Sierra, read my Upgrade Tips for High Sierra, and feel free to let me know if you have any comments or questions.










2 thoughts on “High Sierra, APFS, and your hard drive-equipped Mac

  1. Ines says:

    Hello, Peter,

    I wonder if you have a word of advice. I installed Office 2016 on my Mac Pro, however, I cannot find it. I see it in the hard disk, but have not way of activating it. I tried different troubleshooting tips I found in in the internet, but nothing seems to work.

    Thank you,


    PS. I tried to leave this in your Contact Me section, but it wouldn’t validate the text below.

  2. Peter says:

    Hi, Ines. If Microsoft Office 2016 installed on your Mac like it did on mine, you should see the individual office apps inside your Applications folder. Launching any one of them should commence the activation process if they’re not already activated.

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