Download the High Sierra full installer from the App Store to your iMac.Then install HS to your SSD. IF you want to use the APFS file system then you will instead need to format your SSD APFS before installing HS. To do this you must use High Sierra's Disk Utility. So, if you have HS installed on your iMac you can do it from there before launching the HS installer. Or you will have to make a USB thumb drive installer of HS and boot from it, then format the SSD as APFS from Disk Utility and install HS.If the SSD were your internal drive then the APFS file system would be automatic. But, you have an external enclosure with your SSD so HS sees this as an HDD and won't auto convert to APFS. This is why you have to manually format it.After your install of HS, you can use Setup migration to migrate your user accounts, data, apps and settings over to the SSD.
Answer from keg55 on discussions.apple.comiSkysoft
How to Install macOS High Sierra on External Hard Drive
May 5, 2022 - You will need an external drive ... copy of the macOS High Sierra installer. You can obtain the installer from the App Store by searching for "macOS" and download it to your Mac hard drive. ... To allow the external drive to function as the startup disk, you need to format ...
How to Install High Sierra on External Drive - Ask Different
apple.stackexchange.com
How to Install High Sierra on External Drive - Ask Different
I'll try to keep this as simple as possible but it's a little complicated. I am trying to install High Sierra on an external disk. The computer I'm using is running Mojave, however, so it won't r... More on apple.stackexchange.com
Install High Sierra or higher on a Partition | Mac-Forums | Fix Mac iPhone iPad | Buying Tips | iOS OS Help
mac-forums.com • 28 • July 8, 2022
Install High Sierra or higher on a Partition | Mac-Forums | Fix Mac iPhone iPad | Buying Tips | iOS OS Help
28
• July 8, 2022At some point if I decide to keep this I will need to move High Sierra to the iMac fusion drive. I have lot's of space. ... I guess it is best to use Migration Assistant. I am not sure how I would take a Time Machine El Capitan backup and move the data to El Capitan on the USB disk partition. Comments. ... Migration Assistant is probably the easiest the way to go. As you experienced...since one of the drives is external ... More on mac-forums.com
Can't use high sierra on external drive on new 2020 imac running Catalina
r/macsysadmin • 5 • March 16, 2021
Can't use high sierra on external drive on new 2020 imac running Catalina
5
• March 16, 2021You can’t. The new 27” iMac will only run macOS 10.15 or newer since the hardware was introduced when Catalina was the latest macOS version. More on reddit.com
Install High Sierra on external drive... | MacRumors Forums
forums.macrumors.com
Install High Sierra on external drive... | MacRumors Forums
I am not willing to install High Sierra instead of Sierra as of yet. ... Sure you can do that to try it out. It'll work fine. ... Hello, High Sierra on an external SSD is my exact setup. it's on a 250 g Samsung. Fast and furious, Also I have Sierra and Mojave and El Capitan on another external SSD. More on forums.macrumors.com
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Wondershare
[Tips] Install macOS Sierra on External Hard Drive
Before you install macOS Sierra on the hard drive, you will need to clean the external device. Ensure that there is no important data on your hard drive. Then plug it into your Mac, go to Finder, and select Applications. From Applications, go to Utilities and from there, find and double click ...
Apple Support
Install macOS on an external storage device and use it as a startup disk - Apple Support
April 2, 2025 - If you have an external storage device, such as a USB or Thunderbolt drive, you can install macOS on that device, then use it as a Mac startup disk. ... Make sure that your storage device is plugged into the appropriate port on your Mac. If you're using a Mac with Apple silicon, plug your storage ...
Stack Exchange
How to Install High Sierra on External Drive - Ask Different
I also tried booting into internet recovery and installing directly from there onto an external drive, eliminating the bootable USB installer from the equation. Same result: when restarting it just boots to the OS on the internal drive and doesn't complete the installation.
Mac-Forums
Install High Sierra or higher on a Partition | Mac-Forums | Fix Mac iPhone iPad | Buying Tips | iOS OS Help
July 8, 2022 - ... I guess it is best to use Migration Assistant. I am not sure how I would take a Time Machine El Capitan backup and move the data to El Capitan on the USB disk partition. Comments. ... Migration Assistant is probably the easiest the way to go. As you experienced...since one of the drives ...
Macworld
How to install macOS on an external drive | Macworld
September 14, 2024 - Follow these instructions to prepare your external drive – note that there may be some slight changes to the process if you wish to install macOS Ventura or the latest macOS beta. Connect the external drive to your Mac. Launch Disk Utility (press Cmd + spacebar and start to type Disk Utility).
Quora
How can I use a USB drive to install XOS High Sierra? I'm using macOS Monterey.
Answer: Before you waste time trying to create a bootable installer with a USB flash drive, consider that not every Mac can run High Sierra as well as your more modern Monterey. You first need one of these to be able to install and boot up this old operating system AND run Monterey. * MacBook ...
MacRumors Forums
Install High Sierra on external drive... | MacRumors Forums
I am not willing to install High Sierra instead of Sierra as of yet. ... Sure you can do that to try it out. It'll work fine. ... Hello, High Sierra on an external SSD is my exact setup. it's on a 250 g Samsung. Fast and furious, Also I have Sierra and Mojave and El Capitan on another external SSD.
Reddit
r/hackintosh on Reddit: Succesfully installed High Sierra on external HDD without even switching to iGPU. Literally everything works!
December 29, 2021 - in my case only a few app store apps aren't compatibile (some running on older version, some on the newest) but the biggest problem is Pixelmator Pro which is not working on High Sierra. i see in the future what else can't run on my version ... Literally everything works!
YouTube
How to create a bootable macOS High Sierra USB Install drive - YouTube
03:12
A bootable USB installer is a handy tool for fresh installs of macOS High Sierra. Subscribe ► http://bit.ly/9to5YT | Read full article ► http://wp.me/p1xtr9-
Published: August 2, 2017
Views: 761K
Idownloadblog
How to create a macOS High Sierra 10.13 installer on a USB drive
January 26, 2023 - This guide will show you how to create a USB installer for the new macOS High Sierra operating system, which is useful for clean installs and easy deployment to multiple machines.
iFixit
How to Install macOS High Sierra - iFixit Repair Guide
Note: If you’re trying to install the latest MacOS on a 2009 and later Apple computer, follow the MacOS internet recovery guide instead. If you...
OWC
How to Perform a Clean Install of macOS High Sierra
September 24, 2019 - However, there’s an easy way ... disk · When you’re done with steps 1 and 2, you can proceed to the scary part — erasing and reformatting your Mac’s boot drive. Step 3: Erase and Reformat the Mac’s Boot Drive Make sure that the bootable macOS High Sierra installer you just created is connected to your Mac, whether it’s a USB flash drive or an external hard ...
Mac Help Forums
How do I install macOS Sierra on a blank hard drive? | Mac Help Forums
March 10, 2023 - I've recently got my hands on a unibody iMac from 2010. It already had Sierra installed on it, but the hard drive was partitioned frankly stupidly. The hard drive had a capacity of 1TB, but only about 17GB was usable as the boot partition. That partition couldn't be edited in any useful way, so...
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How to Clean Install macOS 10.13 High Sierra?
December 17, 2024 - External Storage: Manually copy important files to an external hard drive, such as documents, photos, and essential app data. Cloud Backup Services: Use iCloud or a third-party service like Dropbox or Google Drive to save files you may want quick access to after the installation. Make Bootable Clone: You can create a full bootable clone backup for macOS High Sierra with third-party disk ...
TechToro
How to Install macOS High Sierra: The Full Guide - TechToro.io
December 23, 2024 - The first step to install macOS High Sierra is to power off the device and disconnect all external drives (hard disks and flash drives).
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How to Install macOS on External Drive(Sequoia & Earlier)?
4 weeks ago - This post tells how to install macOS on an external drive on Mac, you can follow the detailed steps to install macOS Sequoia, Sonoma, Ventura, Monterey, and earlier versions on external drives.
Mackeeper
How to Create a macOS High Sierra Bootable USB
April 30, 2025 - Therefore, Time Machine will ask ... your external hard drive. That’s it, let Time Machine back up your files. Go to System Preferences > Time Machine and click on Select Backup Disk · For a more detailed guide, check out our article on how to back up your Mac using Time Machine. Launch the App Store. Type High Sierra in the upper right search bar, and download the High Sierra installer...