Installing Catalina on an External Drive
I'm using a late 2013 27" iMac that is running Mojave 10.14.8, and would like to run Catalina from an external drive. I have a T7 SSD and have formatted it as APFS format with GUID partition map. I run the Catalina installer selecting first "Show all Disks" and then selecting my SSD which I named "Macintosh Catalina" during formatting. When the installer finishes it restarts my Mac which boots to the existing Mojave OS. In system preferences under Startup Disk Macintosh Catalina does not show up. Looking at Macintosh Catalina in the finder in the finder I find a single folder named macOS Install Data:
This is not what I expected.
The procedure I used is from an article by MacWorld: How To Install macOS On An External Drive | Macworld It is lacking some important points. It says to use the GUID partition, but never mentions AFPS. Luckily I was aware and did format the disk AFPS.
Where did I go wrong?
iMac 27″, macOS 10.14