A friend of mine bought an external Seagate 5 TB drive. He kept it formatted as exFat, and it worked good for a day or so. But today it doesn’t mount. So I am trying to help him format it again (as APSF), but it is impossible.
I have tried with Disk Utility and with diskutil in Terminal, to no avail. Some facts:
- In Disk Utility, the disk (named “Server”) is greyed out.
- Trying to erase it* shows after a while that it couldn’t unmount the drive (error 69879).
*I have tried both the volume as well as the actual disk.
- All actions in Disk Utility gives the error “Can’t unmount the drive”.
- In Terminal I have similar problems. diskutil eraseDisk gives “Couldn’t unmount disk”
- diskutil unmountDisk force disk2 actually works. If I then do a “diskutil eraseVolume HFS+ Server disk2” it starts to erase it, but after 20% or so it cancels with Error: -69888: Couldn’t unmount disk…
I also tried a cs list, but it couldn’t find any (ie encrypted partitions).
Please note that the disk is NOT mounted in any way (as I said, it’s greyed out in Disk Utility). I suspect that macOS is trying to talk to the volume and thus occupies it in some way.
So, any ideas…?