umount不了磁盘或者网络设备

比如umount不了/g01/app/shared

[root@rac01 shared]# umount /g01/app/shared
umount.nfs: /g01/app/shared: device is busy
umount: /g01/app/shared: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
umount.nfs: /g01/app/shared: device is busy

此时你当然可以用-l强制umount，

umount -l /g01/app/shared

但是有方法可以查谁在使用这个设备，方法很简单
fuser

[root@rac01 shared]# fuser -u /g01/app/shared
/g01/app/shared:      1520c(root)
[root@rac01 shared]# ps axu|grep 1520
root      1520  0.0  0.0 108468  1912 pts/0    S    09:00   0:00 bash
root      1630  0.0  0.0 103256   840 pts/0    S+   09:09   0:00 grep 1520

之后ps查一下进程，发现是bash进程在占用，退出目录然后umount就ok了。