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User profile for user: Jseegs
Jseegs Author
User level: Level 1
9 points

Unable to erase SSD

Hello everyone,


My 2015 27" iMac recently crashed and will not startup. The internal SSD is full to the point where I am unable to delete anything, even Time Machine is unable to restore a backup because of this.


I currently have Catalina installed on a SD memory card and get boot up MacOS off of the memory card. From there I can view my SSD, but I am still unable to delete anything to clear space. I've tried deleting files from the terminal with no luck.


I've also tried reformatting the drive using the disk utility, when I do this I get an error saying the drive is in use and couldn't be unmounted due to process 0 (kernel) even though I've booted up on the memory card, not the SSD.


I've tried internet recovery mode, but I have no luck connecting to my wifi network, and cannot get internet recovery to make use of ethernet.


My next step is trying to install using a USB installer (but don't currently have a USB drive large enough).


I don't believe the SSD is dead because I'm still able to access it when booted on the memory card, I was also able to copy files off the SSD to an external drive.


Any suggestions would be very appreciated, thank you!

Posted on Aug 4, 2020 1:13 PM

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User profile for user: Kappy
Kappy
User level: Level 10
361,765 points

Posted on Aug 4, 2020 1:27 PM

The SSD will have to be reformatted to become usable. Since you can access the SSD, I suggest you backup your data. When that is finished, use Disk Utility to erase the SSD. You can then install macOS from scratch using Network Recovery.


Internet/Network Recovery of El Capitan or Later on a Clean Disk


     If possible, back up your files before proceeding.


  1. Restart the computer. Immediately, at or before the chime, hold down the (Command-Option-R) keys until a globe appears.
  2. The Utility Menu will appear in from 5-20 minutes. Be patient.
  3. Select Disk Utility and click on the Continue button.
  4. When Disk Utility loads select the target drive (out-dented entry w/type and size) from the side list.
  5. Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
  6. Set the partition scheme to GUID.
  7. Set the Format type to APFS (SSDs, only if installing Mojave or Catalina ) or Mac OS Extended, (Journaled.)
  8. Provide a volume name, usually "Macintosh HD."
  9. Click on the Apply button, then click on the Done button when it activates.
  10. Quit Disk Utility and return to the Utility Menu.
  11. Select Install OS X and click on the Continue button.


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User profile for user: Kappy
Kappy
User level: Level 10
361,765 points

Aug 4, 2020 1:27 PM in response to Jseegs

The SSD will have to be reformatted to become usable. Since you can access the SSD, I suggest you backup your data. When that is finished, use Disk Utility to erase the SSD. You can then install macOS from scratch using Network Recovery.


Internet/Network Recovery of El Capitan or Later on a Clean Disk


     If possible, back up your files before proceeding.


  1. Restart the computer. Immediately, at or before the chime, hold down the (Command-Option-R) keys until a globe appears.
  2. The Utility Menu will appear in from 5-20 minutes. Be patient.
  3. Select Disk Utility and click on the Continue button.
  4. When Disk Utility loads select the target drive (out-dented entry w/type and size) from the side list.
  5. Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
  6. Set the partition scheme to GUID.
  7. Set the Format type to APFS (SSDs, only if installing Mojave or Catalina ) or Mac OS Extended, (Journaled.)
  8. Provide a volume name, usually "Macintosh HD."
  9. Click on the Apply button, then click on the Done button when it activates.
  10. Quit Disk Utility and return to the Utility Menu.
  11. Select Install OS X and click on the Continue button.


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User profile for user: TheLittles
TheLittles
User level: Level 10
192,889 points

Aug 4, 2020 1:34 PM in response to Jseegs

Jseegs Said:

"Unable to erase SSD: [...]My next step is trying to install using a USB installer (but don't currently have a USB drive large enough)[...]"

-------


Use a USB Flash Drive that is 16GB.

Trying the USB Bottle Installer is way to go from here. - Do you have one laying about? If not, just get one at your local retailer.


For Note: 8GB are tough to come by as individual packs, as they are now becoming more, and more, obsolete. So, you'd probably only find an 8GB USB Flash Drive in a multipack.

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User profile for user: Jseegs
Jseegs Author
User level: Level 1
9 points

Aug 6, 2020 7:10 PM in response to Jseegs

Just to follow up, the USB bootable installer was successful, though I continued to get error -69877 when trying to erase the SSD using the disk utility. The disk utility would not let me unmount the SSD saying that it was in use. I used the terminal command


diskutil unmountDisk force disk1

(I found help in this thread https://discussions.apple.com/thread/5812340)


which then allowed me to format the SSD in the disk utility and get Catalina reinstalled.


Thanks again for all the help!

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User profile for user: Jseegs
Jseegs Author
User level: Level 1
9 points

Aug 4, 2020 1:33 PM in response to Kappy

Thank you for the help!


When holding command-option-R I'm able to enter internet recovery mode. However, when prompted for my wifi password I'm simply sent back to the network selection page.


I've also tried entering internet recovery using an ethernet cable and no wi-fi by there doesn't seem to be a method for the ethernet connection to be selected.

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Unable to erase SSD

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