umount of a normal filesystem weirdly failed

[albert_hua]

Hi,
I encountered a strange question.
One day I found one normal file system 100% then I went into the mount point and used the command 'du -xk .' to list the usage situation but I found the used size is far less than the total size but the result of 'df -k' showed the filesystem was full. I used 'du -r .' to check whether there was any files could not be opened but no errors found.
Then I decided to umount the filesystem and remount it in order to make system update the information. But I failed to umount this filesystem although I used 'fuser -kc mount_point ' and 'fuser -ku special_file_name ' to kill any user using the file system. I was always told 'Device Busy' by the system. So I think it is a little difficult to explain what possess the rest blocks of this filesystem.
Could you give me any reasonable explanation or solution ? Thanks a lot!

[G. Vrijhoeven]

Hi,

Was it a vg00 file system?

Gideon

[albert_hua]

No, it is a normal filesystem created on other VG.

[steven Burgess_2]

Hi

Please forgive if i'm incorrect, but your current directory at the time of attempting to action the umount was the actual 'mount point?'

Steve

[albert_hua]

Hi,
Certainly.

Thanks
Albert

[steven Burgess_2]

Hi

Sorry,

If you were in the mount point at the time of attempting you umount you would get the message device busy. You need to be in the root (/) directory

Steve

[albert_hua]

Hi,
Certainly I am in the '/' directory.
Thanks.

Albert

[Roger Baptiste · Accepted solution]

hi,

There could be some process writing into that filesystem and whose open file pointers no longer exist. Check it using lsof . Free download from
http://hpux.cs.utah.edu/hppd/hpux/Sysadmin/lsof-4.61/

That will give some clue on what processes are writing into the filesystem.

Another reason why it may not be unmounting could be because it has a nested mount. You can verify this by running
bdf | grep "mountpoint" .


HTh
raj

[albert_hua]

Hi, RajMan:
I think you are right and I will try as you told me. Thanks a lot!

Albert