Often It happens device remains busy during unmounting a device(CD, Disk or NFS shared partitions) on Linux. It is good idea Linux should tell you what is keeping the device busy? We are using Centos, and message remains same in all the time we have used Linux.

The First step all users prefer will be to close down all your terminals and xterms. There is a better way. You can use the fuser command to find out which process was keeping the device busy:

The fuser command’s ouput something like this.

The above command shows us that there is a process running with the prosses id 3172 we just need to kill that process then we can easily umount the /dev/sda6

That is now you can easily umount /dev/sda6. There is another hack you can you and that is passing the -l option to umount any bussy device e.g.

Above command causes lazy umount which detaches the partition from the filesystem, it is useful if it is a networked file system (NFS) and the network has gone down.

That’s all enjoy.