FreeBSD: Forcefully unmount a disk partition to get rid of device busy error

Posted on in Categories last updated August 28, 2006

Under FreeBSD if you get error device busy while unmounting file system then you can forcefully unmount a disk partition or mount point. You can pass -f option to mount command. It forces the read/write mount of an unclean file system. Suppose you would like to unmount /cdrom forcefully then type command (login as a root user use su or sudo command):

# umount -f /cdrom

Where,

  • -f : Forces umount to unmount a disk partition or mounted system

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

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  1. Before you do this you should always check what process is keeping your device busy:

    Install “lsof” from ports and run:

    #> lsof /dev/

    This will output a list of users and processes using this device. Then kill one by one and try to unmount again. If no process is using it but you still get the error use the command in this hint above.

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