Preparing your Fusion Drive Mac for the macOS High Sierra install

Via Apple:

Beta versions of macOS High Sierra made a change in the disk format of systems by converting them to use the new Apple File System. The initial release of macOS High Sierra will provide support for the new Apple File System as the default boot filesystem on Mac systems with all-Flash built-in storage. If you installed a beta version of macOS High Sierra, the Fusion Drive in your Mac may have been converted to Apple File System. Because this configuration is not supported in the initial release of macOS High Sierra, we recommend that you follow the steps below to revert back to the previous disk format.

Read more in the full article here.

MacDailyNews Take: Before proceeding, BACK UP YOUR DATA.


      1. To all Apple Fusion Drive High Sierra OS updaters out there:

        A clarification from Apple was emailed to me when I inquired about Apple Mac Fusion Drive(s) and High Sierra OS functionality problems being listed on the Apple centric websites.

        Apple responded within hours of my inquiry today.
        The response/clarification was from a very Senior Apple Management Official–

        “Hi ********,

        There seems to be some confusion here. The initial release of High Sierra absolutely will run on Fusion-based systems (I’m using one on my desk right now). It simply won’t be using the APFS file system on the boot volume. That support will be added in a subsequent release.

        Hope this helps clear up the confusion.


        – *************

  1. Yeah the APFS change is a big one. Have multiple backups of important files/pics/videos in various clouds/drives. I’ve been playing with the Beta for a while and lets just say there are still some gremlins.

  2. Ok, so it is required to create a temporary installer assistant in an external HD? It is also required to reformat the main drive. What happened to, “it just works”. To me this is not a big deal, but to other folks, they will not use the new file system, just because of this.

  3. Install a SSD instead of the outdated Fusion kludge.

    Oh wait, Jony doesn’t want you to ever see the inside of your glued together Mac.

    Okay, add to your bag of adapters an external hard drive. Pay the Thunderbolt tax and pretend you got a good bargain. Start saving now for the next generation MBP and hope that Apple remembers to make it user friendly again. Sigh.

  4. Thankfully, High Sierra is still in beta. It’s not ready for prime time.

    Even when it’s officially released, I will NOT be upgrading to High Sierra until developers adapt to the APFS file format. That’s going to take MONTHS. I’m most specifically talking about every disk repair utility. Relying only on Apple’s Disk Utility is not acceptable in my world.


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