Best Way To Install High Sierra

Hi there, thanks for this forum.

I’m running OSX 10.12 Sierra. I like my setup and don’t want to change it.

However, in order to run one software I need High Sierra, so I’m thinking of installing 10.13 on an external drive which is connected to my Mac via Firewire.

Ideally I’d like to partition the external drive in to two partitions, and use one partition for backing up my Mac (10.12), and another partition for running 10.13.

Much of what I’m reading via Google is confusing me, so I thought I might seek your advice. Is installing High Sierra on an external drive any different than installing any other version of OSX?

Many thanks!

Can I divide a drive in to two partitions, and use one partition to backup a Sierra drive, and the other partition to run High Sierra?

So I succeeded in making a bootable USB installer for High Sierra using Terminal. That went smoothly.

The installer won’t install however. I can boot from the installer, choose a destination drive, and the installation begins. But it never ends.

At one point the installer threw up an error saying only “rebooting because of a problem”.

It appeared to try to install again, but the process ended when a small circle appeared on the screen with a line through it. The circle remained for 10 minutes, so I powered down.

If it helps, I’m trying to install High Sierra on to a 1TB partition of an external drive. Here’s a screen shot of that drive from Disk Utility.

Screen Shot|662x468

Some files were installed on the target drive, including a folder called something like Incomplete Installation, which appeared to contain some files which weren’t correctly installed.

Apple has given me exactly no useful information about the failure, so I’m stumped as to next steps.

Thanks for any assistance.