Moving external boot drive to a new iMac

Apr 24, 2022
Reaction score
I have a late 2015 iMac. My 2TB fusion drive started failing so I purchased a 2TB external SSD and used migration assistant to move everything to the new external. This works very well except there are times when the os tries to access the internal HD and causes lengthy beach balls. Bootup can sometimes take 10 minutes or more, I assume because it's trying to access the defective internal for some reason. I have the option of buying a used 2019 iMac but it only has a 512GB internal SSD. Would I be able to seamlessly move my current external SSD to the 2019 iMac and boot from it as I am doing now?


Cory Cooper

May 19, 2004
Reaction score
Hello and welcome.

Sorry for the delayed response.

When you did the migration, did you migrate everything including macOS and are you starting up from the external? If you are still running macOS from the internal and it is failing, then that could cause the issue. If you did a complete macOS install and migration to the external, then it would be best to wipe the internal so there isn't anything for the system to access.

Theoretically, you would be able to attach the external to a 2019 iMac and startup from it.


Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question