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Can I run macOS from external hard drive?
Installing the Mac operating system on an external drive is the safest way to get a good look at a new OS without changing anything on your Mac. Prepare the external drive for the installation using Disk Utility. Get the macOS install files – we’ll show you how.
How do I run a version from an external hard drive on a Mac?
Install macOS on your external hard drive
- Open a new Finder window.
- Navigate to the installer that you want to use.
- Click to launch the installer.
- Click ‘Continue.
- Read the terms and conditions, and if you’re happy to proceed, then click ‘Agree,’ followed by ‘Continue.
Is it possible to boot OS X Mountain Lion from a flash drive?
Thankfully it’s still possible to create a bootable OS X 10.8 Mountain Lion installer from any USB drive, be it a flash key or external hard drive. By creating a bootable install drive, you can perform clean OS X 10.8 installs, install it on separate partitions, and install OS X Mountain Lion on Macs that don’t have internet connections.
How do I install mountain lion on my Mac?
One is to go to System Preferences -> Startup Disk -> and select the USB drive. This will load up the Mac OS X Mountain Lion installer as soon as you restart your computer. The other method is to simply hold down the Options key on the keyboard when your Mac is just turning on after being shutdown/restarted.
Why is there no disk when trying to install Lion?
From what you describe it sounds like you are trying to install Lion on your newly installed HDD replacement but its not showing as a disk when you try to actually install Mac OS X. That indicates to me that the drive has not yet been formatted as Mac OS Extended Journaled, so it is not ready for Lion to install onto it.
Can you install OS X from a USB flash drive?
If you need to install multiple copies on a few computers, or even prefer not to have to download a new copy every time you have to install the Mac OS. And from what I’ve experienced, installing from a USB Flash drive is faster than installing via downloading a new copy from the Mac App Store or even from DVD.