macOS High Sierra [Production Release] Flash Drive Installer Instructions

High Sierra

High Sierra

Apple has released the official version of macOS High Sierra if you want to create a flash drive installer, to be able to install it on multiple Macs without having to download it over and over again or if you like to have a safety net just in case your disk crashes at any time. The normal process that Apple offers for any operating system install will automatically erase the installer, when the install in completed, so a special procedure is needed to create the flash drive before you run the installer, as follows.


Degree Of Difficulty: Medium

If you have enough skills to format a flash drive and to use the Terminal to issue one UNIX command then these instructions will be very easy for you to follow, if not then have someone guide you through the process so you don’t unintentionally erase your entire hard drive. You’re responsible for your own outcome.

Compatibility Check

First things first, because of a weird con job that Intel pulled on Apple, older Macs will simply not be allowed to install High Sierra.

Check the following list to be sure that you Mac is qualified to run Sierra:

  • iMac (Late 2009 or newer)
  • MacBook Air (2010 or newer)
  • MacBook (Late 2009 or newer)
  • Mac mini (2010 or newer)
  • MacBook Pro (2010 or newer)
  • Mac Pro (2010 or newer)


I have personally performed this install on my own Macs at home and it worked fine, you are on your own if you run into any issues so make sure this type of project is appropriate for your skill level and resources.


As always when performing anything that has potential risk with your computer, its important to have at least three backups before you proceed. There is nothing worse than experiencing a catastrophic failure, losing all your data, phone numbers address, medical notes and other vital information that is an integral part of our lives today.

  • Three backups
    • Three is the minimum number of backups you should have in order to have confidence that you can recover your system. The logic behind this concept is that if your first attempt to restore your system fails from backup #1, the average person’s inclination will be to try backup #2, but what happens if backup #2 fails? You now don’t know if you simply had two defective backups or if the system you are using to perform the restoration on is destroying your precious backups. At this point you should take backup #3 to a highly qualified tech or engineer and have them carefully restore your system.
  • Verify backups
    • Its surprising to see how few people actually check to see that their backups work, only to find that they fail right at the moment you need them most. Test your system and be sure.
  • Make sure that you know how to restore your system
    • Of the people that do perform backups, few know ho two actually restore that backup. Like anything else, practice is key to success.
  • Offsite backup
    • Keep one or two backups onsite, and at least one backup copy offsite. If anything happens at your main location, fire, flood, etc. then that offsite backup is all you will have to restore your digital life.
  • Time Capsule
    • Apple’s Time Capsule is the best, easiest to use, most reliable backup system for home or small businesses that I have ever seen. Time Capsule is a brilliantly simple and elegant concept, typical of Apple’s ingenuity. Its actually a WiFi access point with a built in hard drive. This allows all the devices in your home to access the Internet and any Macs to automatically backup to the time Capsule with no extra effort.
      • Setup of the Time Capsule is ridiculously simple:
        • Plug the ethernet cable into the Internet router
        • Launch the Airport Utility from any Mac, iPhone or iPad that is in range of the network
        • Follow the on screen instructions and within moments you’ll be on the Internet.
      • To add a Mac to the Time Capsule so it can be backed up is also very easy.
        • Connect the Mac to the Time Capsule network
        • If the Time Machine app on your Mac asks you if yo want to add this Mac to the Time Capsule, accept the invitation.
        • If the Time Machine app sides not automatically ask you anything, then open Time Machine Preferences (from System Preferences or from the Time Machine widget in your menu bar) click Select Disk and add the Time Capsule.
      • Time Machine (which is the built-in Mac software that communicates with your Time Capsule) will automatically now backup your Mac every hour. Thats it. It truly is the simplest backup system I have ever seen. Its also the most reliable backup system I have ever experienced. I can’t tel you ho many times I’ve had to to recover a major corporation by hand from offsite backups because their million dollar onsite backup system failed. Its a rarely spoken of phenomenon but the storage systems fail more often than the average consumer is ever aware of and the backup systems often fail to work completely, which is why you sometimes experience a company that can’t access your records or messes up your accounting. Time Capsule has worked for me every time (yes I have checked to see that my backups are valid and that I can actually recover files) and have recommend it for years with success, to all my family and friends.
      • For ultimate protection I always insist that my family and friends plug their Time Capsule into a UPS to protect from power surges and to give you a few minutes to shut down your computers gracefully (which also shuts down backups gracefully) so you don’t lose any data.
    • Apple  Time Capsule on Amazon.

Target Media

Although this post refers to flash drives, it works equally well with any external USB or Thunderbolt hard drive.

Clean Install: The Myth

Its often repeated that performing a “Clean Install” is best to get rid of old gremlins that may have creeped into your system. I’ve been experimenting with this premise for years, to see where the truth actually lays.

What I found is that although you can get rid of weird gremlins using this method, it takes a huge amount of time to return your system to the custom configuration that you’ve worked on unknowingly over the years. If you do have gremlins, its far less trouble and effort to simply remove old drivers and replace them with new ones. The actual likelihood that these kind of gremlins happens to any given user is extremely low since macOS is the originator of Plug & Play so there typically are no drivers that you need to replace.

What became much more apparent is that Windows users that have migrated to the Mac are the source of this myth, because they mess around with the operating system (like they had to do with Windows) and actually insert the very problems that they later complain about.

If you do add a component to your Mac that requires a driver install, and if you then have gremlins, then simply remove the driver and reboot, if the gremlins disappear then its obviously not a gremlin problem, its the fault of whomever provided you the driver, go gripe at them and don’t reinstall it until they have proven that their driver works perfectly.

Another myth is that the leftover configuration or preference files leftover when yo delete an unneeded app somehow cause problems. No they can’t. Its true that there are enormous file (library) dependencies in M$ Windows and that deleting one of them when its needed by other programs, can result in enormous headaches (hence all that tinkering by those Window users) but that obviously problematic methodology just does not exist on macOS. Macs have one set of preference files for each app. No other app reads those files and so it does not matter if those preferences are there or not. In fact, you can simply delete those preference files and typically the application that uses them will simply install a fresh copy without you even knowing about it.

That same bit of drivel goes on to say that these leftover preference files take up too much space and must be removed. No and no. They are tiny files and it causes no had to leave them alone. The space they take up is minuscule which means that going through all the trouble of finding and deleting them to save on one to ten megabytes of space (assuming you have has macOS since 2000 and simply upgraded it each time, without performing clean installs) just isn’t worth it. One JPEG image typically uses two or three megabytes of space so if you are worried about saving a tiny bit of space then delete the thousands of JPEG pics that everyone has on their system and then you will have a far greater impact than removing a few tiny preference files.

Cache files, are always implicated in the Clean Install myths and for once there is a grain of truth. Its unlikely that a corrupted or outdated cache file will cause you grief, but its possible. There is no button to push to flush out the caches, because no OS manufacturer sees it as an issue and the cache files are there to improve the performance of your system so they are intended to be left alone. You could reboot your system to see if the cache file in question is flushed out (they get automatically rebuilt when needed) which sometimes does work.

Cache corruption is not a common problem but if you are sure that its causing you some problem then reboot your Mac in Safe Mode (hold down the Shift key while booting up). macOS will clear out the System caches for you and check the filesystem (this takes extra time to boot up, be patient). If that doesn’t work then reinstall the errant app. If it still doesn’t work then use a cache cleaning utility to get the job done.

All of the following apps will get the job done, and if you’re truly a geek then I don’t need to tell you that you can remove them for free by yourself, since you already know that. These apps all work to the same degree of effectiveness, plus they have a lot more extra features for system maintenance that might appeal to you.

Clean My Mac [$39.95]

High Sierra Cache Cleaner [$15]

OnyX [Free]

Avoid Leftover Gunk

If you really do wish to avoid building up gunk in the future when deleting Applications from your Mac, then try AppCleaner by FreeMacSoft it is free, has worked perfectly well in my years of testing it. If you set it to automatic mode (which works well) it will then pop up a screen to ask your permission to delete the files that it found for you. You can delete them all (which is what I typically do), or uncheck the ones you want to keep (sometimes I like to keep a particular installer for future use, in case I suspect that it might not be available in the future (it happens). There are other apps that perform this functionality, most notably Clean My Mac (CMM), but CMM has a payment requirement after the initial trial period expires and it does not work any better than AppCleaner by FreeMacSoft, in fact my testing showed that no app would get 100% of the crud out of your system automatically or manually (because they don’t actually know which preference and cache files belong to any given app, they simply preform a crude search and offer to delete what they find) but they do remove the vast majority of the innocuous files which is certainly more than good enough for our purposes.

Source: Clean Install OS X: Fact or Fiction

Flash Drive creation instructions for macOS Sierra:

  • Download macOS Sierra
    • If you already downloaded macOS High Sierra and installed it then:
      • Go to App Store
      • Click on the “Purchased” tab
      • Click on the “Download” button next to macOS High Sierra
      • You can go format the flash drive now while you are waiting for the installer to finish downloading
      • The installer will launch itself after the download has been completed,  do not allow the installer to do the update, quit the installer immediately.
    • If you have not yet downloaded/installed macOS High Sierra then:
      • Go to the App Store and start the download for macOS High Sierra
      • The installer will launch itself after the download has been completed,  do not allow the installer to do the update, quit the installer immediately, this is critical.
  • 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: Untitled
        • 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 minute or two)
    • Quit Disk Utility when complete
  • Make sure that the High Sierra installer, called Install macOS High, 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\ –volume /Volumes/Untitled &&say Boot drive created thank you doctor Bob

  • 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. 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
  • Eject the flash drive
  • Label the flash drive immediately


You may now just plug in the macOS Sierra flash drive into any compatible Mac and launch the installer from the flash drive or simply Reboot while holding down the option key, select the macOS Sierra flash drive from the list of drives and it will take off from there. Do not be surprised if the screen blanks out for minutes at a time, nor if it reboots several times, this is normal. Most system can get this all done in less than 45 minutes or so.

Flash drive for macOS Sierra

For these 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 larger 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 fugue of them)
  • Its very inexpensive


Its convenient to place these SanDisk Ultra Fit flash drives into a tiny zip lock bag 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. Place this bag in a fireproof safe along with your on-site backups.





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