upgrading macos on external hard drive only?


I have a 15" PB running 10.2.8. I also have 250GB external lacie hard drive with a couple of bootable partitions. I have successfully tested my backups by booting off of the external partitions.

Can I test out an upgrade by booting to a mirror on my external hard drive and simply upgrade the external hard drive from 10.2.8 to 10.4? I suspect this will work, but I am asking since upgrades and re-installations of operating systems can sometimes be quirky.


U.S.D.A. Prime
Yes, you can upgrade any of your installations individually. When it comes time to install the update, you will be presented with a list of partitions.