disk utility volume could not be unmounted mac

Disk Utility Volume Could Not Be Unmounted on Mac: Troubleshooting Steps

If you're trying to erase your external hard drive using Disk Utility on a Mac, but encountering issues with the volume being in use by a kernel process, you're not alone. This problem can be frustrating, especially when you need to free up space or reuse the drive for another purpose.

Recently, I faced this issue with my MacBook Air (M1, 2020) running macOS 11.3.1, and an external LaCie 'Rugged' 1 TB Firewire drive. The drive was currently formatted as Mac OS Extended (Journaled) and had a GUID partition map.

When I attempted to erase the volume using Disk Utility, I received the error message 'The volume on disk4 couldn't be unmounted because it is in use by process 0 (kernel).' Despite trying various approaches, I was unable to successfully erase the drive. However, I did discover some interesting workarounds and troubleshooting steps that might help you overcome this problem.

One approach I tried was selecting the 'Force Eject' option within Disk Utility. Surprisingly, this worked just fine, which led me to suspect that the issue wasn't with the drive itself but rather with the volume being in use by a process. To further investigate, I ran First Aid on the physical device instead of just the volume. This allowed me to complete the scan without any errors.

However, even after running First Aid successfully, I was still unable to erase the drive due to the unmount problem. It seemed that the kernel process continued to hold onto the volume, preventing it from being erased.

At this point, I decided to try accessing the files on the drive using Finder and Terminal to see if there were any issues with permissions or file system errors. When trying to delete a file using Finder, I received an 'unexpected error' (code -50). Meanwhile, attempting to use the `rm` command in Terminal resulted in an 'Invalid argument' message.

Despite being unable to rename, delete, or erase files on the drive, it did mount correctly and allowed me to view files with no problems. This suggested that the issue was specific to the process of erasing the volume rather than a problem with the drive's file system itself.

If you're encountering similar issues with your external hard drive, here are some troubleshooting steps you can try:

1. Run First Aid on both the physical device and the volume to ensure there are no underlying file system errors.

2. Select the 'Force Eject' option within Disk Utility to see if this allows you to eject the drive without any issues.

3. If you're using an older Mac, consider upgrading your operating system or trying a different version of Disk Utility.

4. Check for any corrupted files or permissions issues by running `fsck` and `chmod` commands in Terminal.

5. Try erasing the volume again after restarting your Mac to ensure that any kernel processes are released.

By following these troubleshooting steps, you should be able to overcome the 'disk utility volume could not be unmounted' issue on your Mac and successfully erase your external hard drive for reuse or recycling.

Disk utility volume could not be unmounted mac