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OS Catalina, late 2012 iMac - erasing HD data

Can I erase the data on my hard drive without erasing the OS? I messed up loading from Time Machine so would like to erase that and want to start over without also having to reinstall OS Catalina.

Posted on Apr 12, 2021 6:20 PM

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Question marked as Top-ranking reply

Posted on Apr 12, 2021 9:12 PM

In order to start over with Time Machine, you need to erase the entire Mac. You can then re-run Time Machine restore. Below are the steps, and it will erase all data on the Mac:


  1. Shut down the Mac.
  2. Turn on the Mac, and immediately press and hold Command + R until you see the Apple logo.
  3. Once you are in macOS Recovery, verify you are connected to WiFi in the top right corner.
  4. Go to Disk Utility.
  5. Select "View" in the toolbar > "Show All Devices".
  6. Select your main hard drive or SSD. This will be the top, non indented hard drive. 
  7. Click Erase, and input the following exactly: (If you cannot select erase on the main hard drive, erase the "Container" or “Macintosh HD”.)
  8. Name: Macintosh HD
  9. Format: APFS if shown, if not, Mac OS Extended (Journaled)
  10. Scheme: GUID Partition Map (if shown)
  11. Click "Erase". If “Erase Volume Group” is shown, use that instead. 
  12. Quit Disk Utility
  13. Go to the reinstall macOS app.
  14. Follow the prompts, and install on Macintosh HD.
  15. Once done, follow the steps and re-run the restore from backup.


Cheers,


Jack

6 replies
Question marked as Top-ranking reply

Apr 12, 2021 9:12 PM in response to Akpop5

In order to start over with Time Machine, you need to erase the entire Mac. You can then re-run Time Machine restore. Below are the steps, and it will erase all data on the Mac:


  1. Shut down the Mac.
  2. Turn on the Mac, and immediately press and hold Command + R until you see the Apple logo.
  3. Once you are in macOS Recovery, verify you are connected to WiFi in the top right corner.
  4. Go to Disk Utility.
  5. Select "View" in the toolbar > "Show All Devices".
  6. Select your main hard drive or SSD. This will be the top, non indented hard drive. 
  7. Click Erase, and input the following exactly: (If you cannot select erase on the main hard drive, erase the "Container" or “Macintosh HD”.)
  8. Name: Macintosh HD
  9. Format: APFS if shown, if not, Mac OS Extended (Journaled)
  10. Scheme: GUID Partition Map (if shown)
  11. Click "Erase". If “Erase Volume Group” is shown, use that instead. 
  12. Quit Disk Utility
  13. Go to the reinstall macOS app.
  14. Follow the prompts, and install on Macintosh HD.
  15. Once done, follow the steps and re-run the restore from backup.


Cheers,


Jack

Apr 12, 2021 8:05 PM in response to Jack-19

After everything imported from Time Machine, I made the mistake of accepting and pass-wording the profile (user) from my older iMac on the newer one. I had already created a new profile (user) on the new one (which is what I wanted so it would be easier to keep drives, accounts, etc identified separately from older iMac, which will still be used). Instead of answering yes to the question to merge the incoming Time Machine data into the new profile, I opted to keep both - now I see that was a mistake.

I'd wanted to see the imported files, desktop, folders, data, photos under the newly created profile -- instead, it's all under my old profile on the newer machine (with new password). All that shows up when I log into the new profile is only what appears when I installed Catalina.

My explanation is probably confusing. I thot by erasing the data installed from Time Machine, I could then just reinstall from Time Machine and make sure I used only the new profile.

If you understand my issue??? -- is there an easier way to accomplish my desired end result?

Thanks for your time.

Tim

Apr 12, 2021 9:42 PM in response to Akpop5

is there an easier way to accomplish my desired end result


No, there isn't. One of the reasons: if you do not erase the entire drive, you will wind up with two Data volumes (or more if you were to do it again). Those are some of the new features of the newer OS versions.


So,just follow Jack-19's excellent suggestions.

OS Catalina, late 2012 iMac - erasing HD data

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