I had issues unmounting a device, it kept saying device was busy. lsof and fuser showed no device was attached.
I have managed to umount device with the -l option. However, when I plug the hard drive it has incremented to the next device up. e.g. from /dev/sdc1 to /dev/sdd1.
How can I find what's preventing /dev/sdc from being used again? Thanks.