I am going to replace the HDD in my Mac Mini (late 2012)

I put the SSD into a USB 3.0 enclosure, format the SSD and use CarbonCopyCloner to copy everything from the internal HDD to the SSD. Then I swap out the HDD with the SSD and pick up exactly where I left off.

If you have already installed the unformatted SSD into the Mac mini, then you will need to startup from the macOS Catalina installer or your old HDD in an enclosure and first format the SSD.

Then you have a couple of options,

1) you can install Catalina and migrate from your backup.

2) or clone the old HDD to the SSD using CarbonCopyCloner or SuperDuper.

FWIW I always clone the HDD to the SSD because it saves time having to install the macOS and then migrating from the old HDD or a backup.

adz61 wrote:

Thanks for your Reply, to me a while and several reads before I understood what you were saying. I haven't installed the SSD yet, so I think I am going to try your first option. Awaiting delivery of USB 3.0 enclosure.

You're welcome. I done it that way on several occasions, it is actually faster and easier.

Just a few points, which do you prefer CCC or SuperDuper (both new to me)

I've had the paid version of CCC for years. The free or trial version of either can make a one time Clone.

If I format my SSD in the enclosure can I still load OS Catalina from my USB stick,

Yes, then you can migrate from your internal HDD or Time Machine backup.

the reason I ask this is that I have

niggling problem when putting the Mac in sleep mode, I click on sleep, the screen goes off then comes back on again, it sometimes takes 4/5 attempts before finally turning off.

Tried several suggestions all of which appear to work but only for a short time.I am not looking for a solution to this problem because I am hoping it goes away with the new Install.

The sleep wake problem is nothing new. It has been an on going hit and miss issue from Mojave all the way thru to the latest macOS.

FWIW I have the same problem with several Mac mini's using USB Logitech mice. If I touch or move the mouse for the 15 or 20 seconds after selecting sleep from the drop down, the Mac mini pop back on. Even the slightest movement like sliding in my keyboard and mouse tray will disturb them from nodding off.

So after all that here is the six million dollar question, If I were to clone everything from my old HDD would I be importing the above problem onto my new SSD. Sorry if this is a stupid question.

Not a dumb question at all. I would be more concerned about bringing over third-party AV, Cleaning, Optimizing and other junk-ware.

You can do a fresh clean install to the SSD in the external drive. Before doing anything else you can boot to it and see if the issue continues with just the OS to determine if it is something "hiding" in your current drive that is causing the issue.

If the issue does not exist, you may want to do a manual, fresh re-install of your apps and manually move your data to the new drive since a migration can simply import the issue.

If the issue still exists after a clean install, then there is something "endemically" wrong with you Mac and OS combo that is causing the issue. In which case, avoiding using sleep is the only issue.

Regardless of any results, you should fully test the drive in the external enclosure for a few days of use before putting it inside the Mini. While swapping drives in a 2012 Mini is not majorly difficult, it is still a pain none the less and having a known working system before doing the swap could save problems later.

You’re welcome.

Glad to hear that you are up and running on the new SSD.

I suspect the transfer took that long because you were cloning from the stock slow hard drive.