Force stuborn drive to unmount I have a single partition disk whose filesystem will not mount properly. I don't care about the data and I would like to try reformatting the disk but I keep getting errors related to a failure unmounting the drive. I have tried the following in both normal and recovery mode:


reformatting in the Disk Utility GUI
sudo diskutil partitionDisk /dev/disk3 GPT JHFS+ New 0b 
sudo diskutil unmountDisk force /dev/rdisk3
sudo fdisk -i -a hfs /dev/rdisk3
sudo gpt destroy /dev/rdisk3


All of these attempts have yielded errors either saying that the "drive can not be unmounted" or that the "resource is busy". Is this indicative of a hardware issue in the drive as opposed to just a corrupt file system? Is there anything else I can try?
The issue persisted across multiple macs but Windows 7's Disk Management tool didn't seem to have any issues creating a new partition table. Afterwards the drive worked as expected on OS X.