I have an external USB 3.0 SSD coming today that I was going to use as the boot drive on my 2013 iMac. I was planning on using Carbon Copy Cloner to copy my HDD to the SSD and switch to the SSD as the boot drive before I upgrade to Mojave later today. This would leave my internal HDD on High Sierra as I would only be upgrading the SSD to Mojave in that scenario.
I don't plan on using the internal HDD for additional storage as I have plenty of network storage available, so I was going to leave it alone and use it as a backup in the event something goes wrong with the SSD down the road. I was wondering though, should I upgrade the HDD to Mojave first and then clone it to the SSD, or just leave it alone and clone it to and upgrade only the SSD? I'm thinking in terms on future compatibility should I need to go back to the HDD at some later point. I only ask because I don't know if Mojave makes changes to the way things like iCloud or other services work so I don't know if it will cause problems down the road if I were to have to end up booting back to High Sierra on the same machine that I had been using Mojave, if that makes any sense.
I don't plan on using the internal HDD for additional storage as I have plenty of network storage available, so I was going to leave it alone and use it as a backup in the event something goes wrong with the SSD down the road. I was wondering though, should I upgrade the HDD to Mojave first and then clone it to the SSD, or just leave it alone and clone it to and upgrade only the SSD? I'm thinking in terms on future compatibility should I need to go back to the HDD at some later point. I only ask because I don't know if Mojave makes changes to the way things like iCloud or other services work so I don't know if it will cause problems down the road if I were to have to end up booting back to High Sierra on the same machine that I had been using Mojave, if that makes any sense.