Error happens when trying to umount the Lustre file system

Question

When I umount Lustre FS it displays:

[root@cn17663-ens4 mnt]# umount /mnt/lustre 
umount: /mnt/lustre: target is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))

and if I add the force option -f it gives the same result:

[root@cn17663-ens4 mnt]# umount /mnt/lustre -f
umount: /mnt/lustre: target is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))

When I try to list the directory it gives me :

[root@cn17663-ens4 mnt]# ls
ls: cannot access lustre: Cannot send after transport endpoint shutdown
lustre

and I cannot find what the reason is and cannot solve it.

Answer 1

Did you actually try running lsof /mnt/lustre (as the error message recommends) to see what is using the filesystem? This problem is not unique to Lustre, but true of any local filesystem as well - if there is a process using the filesystem (current working directory or open file) then it can't be unmounted until that process stops using it (cd out of /mnt/lustre or close the open file(s)).

Answer 2

I find I can use umount -l /mnt/xx to solve this problem!