Trying to reformat a drive that was used for an employee's Time Machine and Data storage. It is a partitioned drive. Disk Utility failed to unmount the Data partition and reported the TM partition was OK, but I can't eject either without issues:
See attached. I've tried: sudo diskutil eraseDisk JHFS+ Reformat /dev/disk2 ...which resulted in an error -69888: Couldn't unmount disk.
Also tried: sudo diskutil unmount force /dev/disk2 ...which resulted in an error that it was already unmounted or "has a partitioning scheme so use 'disk util unmountDisk' instead"
However: sudo diskutil unmountDisk /dev/disk2 ...resulted in "Unmount of disk2 failed: at least one volume could not be unmounted."
When I try to reboot, the desktop icons disappear, the reboot never finishes and I end up forcing a shutdown via the power button. I've done all of the above several times.