macOS Catalina on an external SSD

[Lnds500]

Hello!

I have a Mac mini (2014) model and yesterday I bought a Samsung T5 meaning to install Catalina on it and run macOS over USB.

I "restored" the SSD through Disk Utility and the first time I booted from the Disk Manager it worked fine. Everything worked, had all my files and applications.

After a reboot I can't get it to boot from the SSD.

"Startup Disk" doesn't recognize that the SSD has an OS installed. Any tips?

 

[Boyd01]

Have you tried holding the option key while you boot? I run my 2012 quad mini on an external Samsung T3 with Sierra, but recently installed Catalina on the internal SSD for testing. When booted into Sierra, disk utility does not see the Catalina disk. To switch, I have to reboot with the option key held down, then choose the Catalina disk. After booting into Catalina, I can then go to disk utility and choose Catalina as a startup drive. Have to do the same thing to switch back to the Sierra startup disk.

Have not tried using Catalina on an external disk however, so that might be different.

 

[Fishrrman]

OP:

What version of the OS is running on your INTERNAL drive?

If it's earlier than Catalina (not sure which version), it may not be able to recognize the APFS disk format and partition structure of Catalina. Thus, the Startup Disk pref pane won't be able to "see" it.

However, the "option key trick" at boot will still work.

You can't change this.
But KNOWING about it, you can just use the option key instead.

 

[Boyd01]

True that you can't change while booted into an older (non-APFS) operating system. However, once you boot into Catalina with the option key, you can then set it as the startup disk using System Preferences.

 

[chrfr]

True that you can't change while booted into an older (non-APFS) operating system. However, once you boot into Catalina with the option key, you can then set it as the startup disk using System Preferences.

Pro tip: If you use the option key boot picker, you can press the control key after you've selected your startup option. The arrow then turns into a circular arrow, which indicates that the new boot selection is permanently selected. There's no need to go into the Startup Disk settings at that point.
It's described here under the "Use Startup Manager" section: https://support.apple.com/en-us/HT202796

 

[Boyd01]

Cool - didnt know that!

 

[Lnds500]

Thanks for all the responses. Both the internal HDD and the external SSD are on the latest version of Catalina.

Will try chrfr's tip and see if it works.

Other that the boot up issue the speed gain is insane! It's a brand new machine!