Loading ...How do I forcefully unmount a Linux disk partition?
It happens many times you try to unmount a disk partition or mounted CD/DVD disk and if you try to unmount device, which is accessed by other users, then you will get error umount: /xxx: device is busy. However, Linux/FreeBSD comes with fuser command to kill forcefully mounted partition.
Understanding device error busy error
What happens basically, is that Linux / UNIX will not allow you to unmount a device that is busy. There are many reasons for this (such as program accessing partition or open file) , but the most important one is to prevent data loss.
Try the following command to find out what processes have activities on the device/partition. If your device name is /dev/sdb1, enter the following command as root user:
# lsof | grep '/dev/sda1'
Output:
vi 4453 vivek 3u BLK 8,1 8167 /dev/sda1
Above output tells that user vivek has a vi process running that is using /dev/sda1. All you have to do is stop vi process and run umount again. As soon as that program terminates its task, the device will no longer be busy and you can unmount it with the following command:
# umount /dev/sda1
Following disussion allows you to unmout device and partition forcefully using Linux commands.
Linux fuser command to forcefully unmount a disk partition
Suppose you have /dev/sda1 mounted on /mnt directory then you can use fuser command as follows:
WARNING! These examples may result into data loss if not executed properly (see "Understanding device error busy error" for more information).Type the command to unmount /mnt forcefully:
# fuser -km /mnt
Where,
- -k : Kill processes accessing the file.
- -m : Name specifies a file on a mounted file system or a block device that is mounted. In above example you are using /mnt
Linux umount command to unmount a disk partition
You can also try umount command with –l option:
# umount -l /mnt
Where,
- -l : Also known as Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. This option works with kernel version 2.4.11+ and above only.
If you would like to unmount a NFS mount point then try following command:
# umount -f /mnt
Where,
- -f: Force unmount in case of an unreachable NFS system
Caution: Using these commands or option can cause data loss for open files; programs which access files after the file system has been unmounted will get an error.
See also:
Want to stay up to date with the latest Linux tips, news and announcements? Subscribe to our free e-mail newsletter or RSS feed to get all updates.
You can Email this page to a friend.
You may also be interested in other helpful articles:
- NFS Stale File Handle error and solution
- Howto to install and boot Debian Linux from an USB device
- Solaris > Safely remove / unmount the floppy disk or cdrom
- Solaris > Forcefully unmount the cdrom/floppy disk
- Linux: How to backup hard disk partition table (MBR)
Leave a Reply
We encourage your comments, and suggestions. But please stay on topic, be polite, and avoid spam. Thank you very much for stopping by our site!
Tags: blk, cleanup, device error, disk partition, filesystem hierarchy, fuser command, kernel version, lsof command, nfs mount, root user, umount command, UNIX, unmount device busy, unmount file system, unmount partition
Recent Comments
Yesterday ~ 1 Comment
Yesterday ~ 50 Comments
Yesterday ~ 3 Comments
07/22/2008 08:38 pm (2 days ago) ~ 10 Comments
07/22/2008 09:02 am (2 days ago) ~ 8 Comments