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this computer originally ran MacOS Sierra and was upgraded over time. Ran Monterey just before I started the migration process. Now just erasing it. Have erased APFSMedia, but can’t get HDD to erase. Error message in Disk Utility says: Unmounting disk; Couldn’t open device; operation failed…
what to do?
Separately, there is an Apple disk image of an OSX Base System external disk that won’t eject. Thoughts on that?
iMac Line (2012 and Later)
You cannot erase the disk that you are booted from. You'll need to reboot the Mac in recovery mode (restart, then press and hold command-R until you see the Apple logo and progress bar).
Use Disk Utility to erase an Intel-based mac - Apple Support
As for the OSX Base System disk image, you can comfortably ignore that. It's irrelevant to your task.
Please confirm that you are booted in Recovery mode when attempting these tasks.
AppleAPFSMedia does not appear to have been erased or partitioned as there are still five APFS volumes listed below.
It also appears to me that perhaps this iMac is (was?) configured with a Fusion drive.
Try this:
• Select AppleAPFSMedia and run First Aid on the drive volumes. Start with volume VM and work your way up, finally running First Aid on the AppleAPFSMedia itself. Run First Aid it until it reports no errors.
• Select AppleAPFSMedia and then click Partition in the toolbar. Use the name "Macintosh HD", select APFS format and GUID partition scheme.
If partitioning the drive still is not an option, you may try first deleting those existing volumes before you can partition the AppleAPFSMedia drive.
Add, delete or erase APFS volumes in Disk Utility on Mac - Apple Support
I love the new process included in Monterey, but per the article you linked:
"…this process only works with Macs running Apple Silicon (M1, M1 Pro, or M1 Max processors) or a Mac with the Apple T2 Security Chip…" 🙁
All good until step 8 of the Apple guidance. Have erased the Mac HD and Update volumes under APFSMedia, so what remains is Apple HDD… In my Disk Utility toolbar there is nothing that says “delete volume”. I opted for erase, but that gives rise to the error message referenced in my original note. (PS: i now see the note that tells me not to worry about external drives - thanks).
When in Disk Utility, click View > Show All Devices.
Then select the uppermost device in the sidebar, usually named Apple Media (or similar) if it's the original internal drive. That is the device that you need to Erase. Can you post a screen shot or pic of what you see in Disk Utility, please?
I suspect you're looking at a split Fusion drive and the possibility that the SSD part has failed.
If you select the AppleAPFSMedia and look at the drive info that is presented to the right of it... does it say "Type: Solid state"?
At this point I'm out of ideas. I realize you're trying to prep this for recycling so I don't know how much time you're willing to spend on it to get the OS reinstalled.
Maybe another user can suggest something?
Here’s the APFSMEDIA, which has already been erased. Will send another photo in a separate post.
Ok thanks. I will try this. I don’t know about a Fusion Drive. The iMac was never augmented in any way following my original purchase.
Starting with VM (NB: grayed out) …No good…
IF you are running Monterey, they follow the steps in https://eshop.macsales.com/blog/78544-how-to-easily-erase-an-mx-macs-data-with-macos-monterey/
Bummer, I missed that. My Mac has a T2 Security Chip so the only method is to boot from the Recovery Partition as you instructed .
Thanks - I’ll try this and let you know. Maybe I bought a new device in the nick of time!
Difficulty erasing late 2015 iMac, for recycling
