umount: /opt/database: device is busy.

卸载出现问题：

root@empty sa]# umount /opt/database
umount: /opt/database: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))

解决方法：

1）使用fuser定位到进程

fuser -m /opt/database

/opt/database:        2505c  2521c  2529c  2587c  2588c  2640c

2）kill掉

kill 2521 2529

3）重新umount