Thunderbolt startup
I have two Thunderbolt ports on my 27-inch iMac, which I believe can run Thunderbolt 1 and 2 devices. How do I set up a Thunderbolt-connected SSD as my Mac’s startup disk?. Giacomo Palucci This is a great way to speed up a Mac with little effort, though it’s costly. If you’ve already bought a Thunderbolt SSD, start by erasing it in Disk Utility, making sure it has a GUID partition scheme and uses theMac OS Extended (Journaled) format.
Get the macOS installer from the Mac App Store and when it asks you to choose a destination, pick the external SSD, of course. You’ll end up with a clean system this way.
Alternatively, make sure you have a complete backup in Time Machine of your Mac’s internal startup disk, start up in macOS Recovery – hold ç+r at the startup sound – and use the Time Machine option there to restore to the freshly formatted SSD. This will put a copy of your existing system on the speedy drive. If your Mac doesn’t restart in the restored system, choose
> Startup Disk, pick the SSD, and then restart.
If you haven’t bought a Thunderbolt drive already and your Mac has USB 3, you can save a lot of money and still get good performance from a USB 3 enclosure with a bare SSD installed in it. The most affordable Thunderbolt “enclosure” we’ve used, which is no longer on sale, was still about $100. We’ve used the USB 3.0 version of this $20 option to try out macOS betas in the past: bit.ly/stenclosure.