umount: /mnt/test: device is busy (In some cases useful info about the processes that use the device is found by lsof(8) or fuser(1)))

If you are getting any such error like below while trying to to unmount the disk follow the steps below to resolve the issue.

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root@server:~# umount /mnt/test
umount: /mnt/test: device is busy 
(In some cases useful info about the processes that use the device is found by lsof(8) or fuser(1)))
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It can be resolved by two ways one can be using lsof and other by fuser.

• For resolving it via lsof follow the steps below we will search the process id and then we will kill that process.

run the command lsof /mnt/test output of the command will be like below snap-shot.

As you can see from the snap-shot 11304 is the process id just kill that process and then try to unmounted. 

1) kill -9 11304
2) umount /mnt/test

• For resolving it via fuser follow the steps below we will do the same thing search the process id and then we will kill that process.

1) fuser -m /mnt/test

Below is the test output

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root@server:~# fuser -m /mnt/test
/mnt/test: 11304
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As you can see that the process id is 11304 now just kill the process id and then try to unmount and we are done.

2) kill -9 11304
3) umount /mnt/test.