High Sierra flash drive installer instuctions

High Sierra

High Sierra

Apple has finally released the Public Beta of High Sierra macOS 10.13, much to the surprise of so many website that erroneously report it being available prior to today, when in fact it wasn’t. Of course we are very excited to test it as quickly as possible. Naturally every Beta has its advantages and its risks so it seems prudent to make a USB flash drive based installer so we can erase and re-install the prototype OS as many times as we need to, without having to waste time and bandwidth downloading it over and over again.

Why bother with the Beta? It satisfies our ned for new features, in particular we are looking forward to moving to a new file system with enhanced features. Apple already deployed Apple File System (APFS) to to iOS users in iOS 10, which has gone so well that the media has reported essentially nothing about it, and now APFS is finally coming to macOS.

The HEVC (h.265) video codec is another much anticipated feature of High Sierra, offering 40% reduction in file size for your video, which can be gigantic and are the number one consumers of disk space for most people. New Macs (2017 models or newer) will have hardware based support for HEVC but it appears that previous systems will handle HEVC in software, which is fine by me, it would be great to reduce my disk space consumption by 40%, even if it takes a while to convert all those videos.

This Beta is high risk, as are all Beta level software, because not all bugs have been discovered and addressed by Apple yet, in this case APFS, being the filesystem itself, could cause severe issues if not throughly tested before we get our hands on it. Since iOS 10 and the developer Beta of High Sierra have gone well so far, it stands to reason that the public Beta version of this update will also do well.

There is an option in the installation process to not convert your drive to APFS, if unchecked it will leave your drive formatted as HFS+ Journaled, which had been working fine for us for many years.

If you do run into issues with the sBeta, please make sure that you use the Feedback Assistant to report the issue to Apple, they really do read all those reports and if verified they will put in on the list to be addressed in due time.

Here are the required steps to create a flash drive for macOS Sierra Beta:

  • Download macOS High Sierra Public Beta (Apple Beta Software Program)
    • If you already downloaded macOS High Sierra Public Beta and installed it then:
      • Go to App Store
      • Click on the “Purchased” tab
      • Click on the “Download” button next to macOS Sierra Public Beta
      • You can format the flash drive now while you are waiting for the download to complete
      • The installer will launch itself after the download has been completed,  do not allow the installer to do the update, quit the installer immediately.
  • Format an 8GB (or larger) drive (it can be a flash drive or any external SSD or hard disk drive), its generally preferred to use a flash drive because they are tiny, inexpensive, don’t waste drawer space and you don’t waste an entire full sized drive on something that can only be used for this installer.
    • Use Disk Utility to format the flash drive
      • Launch Disk Utility
      • Select the flash drive (in the left hand column)
      • Leave the default settings which should be:
        • Name: HighSierra
        • Format: Mac OS Extended (Journaled)
        • Scheme: Master Boot Record
      • Click the Erase button and wait for the formatting process to be completed (it typically only takes a few seconds to a minute or two)
    • Quit Disk Utility when complete
  • Make sure that the beta installer, called Install macOS High Sierra Public Beta.app, is in its default location in your main Applications folder (/Applications).
  • Select the text of this command and copy it:

    sudo /Applications/Install\ macOS\ High\ Sierra\ Beta.app/Contents/Resources/createinstallmedia –volume /Volumes/HighSierra –applicationpath /Applications/Install\ macOS\ High\ Sierra\ Beta.app –nointeraction &&say Boot drive created thank you doctor Bob

    Note: You must copy and paste that command precisely, it has changed subtly since the last Beta.

  • Warning: This step will erase the destination drive or partition, so make sure that it doesn’t contain any valuable data and make sure that you don’t erase your main drive accidentally. Paste the copied command into Terminal and press Return.
  • Enter your password, then press Return.
  • The Terminal window displays the progress
  • Wait until you see: “Copy Complete”
  • This can take as long as 20 or 30 minutes, depending on how fast your Mac’s main drive is, how fast your flash drive is and which interface you’re using (I recommend USB 3.0)
  • Quit Terminal.app
  • Eject the flash drive
  • Label the flash drive immediately

You may now just plug in the macOS Sierra Public Beta flash drive into any compatible Mac and launch the installer from the flash drive. Beware that Beta version of any software can be unstable, it may behave erratically, it can crash your system and you can even suffer total data loss. Be sure to have several known good backups so you can recover and don’t install this on any machine where the loss of use will negatively impact anyone.

Do remember to use the Feedback Assistant app (that the macOS High Sierra Public Beta automatically installs) to report problems to Apple.

I recommend the flash drive that I use, the: SanDisk Ultra Fit™ CZ43 16GB USB 3.0 Low-Profile Flash Drive because:

  • Its tiny (its barely lather than the USB plug itself)
  • Its incredibly fast (I clocked it at 130MB/sec read speed, which is important because each time you use it to perform an install it will have to read the entire operating system, which is approximately 5GB)
  • Its extremely reliable (I’ve never had a failure with one, and I have a zip lock bag full of them)
  • Its very inexpensive

Its convenient to place these SanDisk Ultra Fit flash drives into a tiny zip lock bag, label each one with a permanent marker, to keep them all together for easy access and so they are easy to find and so you can easily select any version of the operating system that you want to install.


  1. Its highly recommended that you make several backups
    1. Have one Time Machine backup and more than one non-Time Machine backup
      1. The Time Machine might not be visible to the OS after the update, which is why you should have different backup methods, such as using Carbon Copy Cloner on a separate drive in addition to Time Machine.
    2. Have more that one backup drive that has macOS already on it and can boot your machine
    3. High Sierra might only appear to be a minor maintenance release, but it has new underpinnings like APFS that can have a major impact if anything goes wrong with the transition. Test your backups and make sure that you can actually boot fro your backup drives before proceeding.
  2. Run Disk Utility and make sure that your disk is in perfect condition before attempting to install the Beta
  3. The Beta installer blanks out the screen several times, then reappears with a new process bar, this appears to be normal, if a bit unexpected.
  4. If possible, plug your Mac into a UPS, or at least a sure protected power strip, to make sure this upgrade process is not interrupted, which could cause significant agony.
  5. Make sure your motherboard battery is OK, it powers the PRAM values which if corrupted can create a mess.
  6. Set aside a bit more time for this upgrade, it needs extra time to do the APFS migration.





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