添加盘：
Disk /dev/sdb: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

[root@single1 test]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3        38G   14G   22G  40% /
tmpfs           495M  202M  293M  41% /dev/shm
/dev/sda1       388M  384M     0 100% /boot

[root@single1 test]# pwd
/test
[root@single1 test]# ls
video.avi

挂载:
[root@single1 ~]# mount /dev/sdb /test
[root@single1 ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3        38G   14G   22G  40% /
tmpfs           495M  202M  293M  41% /dev/shm
/dev/sda1       388M  384M     0 100% /boot
/dev/sdb       1008M   34M  924M   4% /test

[root@single1 ~]# cd /test
[root@single1 test]# ll
total 16
drwx------ 2 root root 16384 Jan 18 18:23 lost+found

 我的video.avi 不见了!!

[root@single1 ~]# umount /test
[root@single1 ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3        38G   14G   22G  40% /
tmpfs           495M  202M  293M  41% /dev/shm
/dev/sda1       388M  384M     0 100% /boot
[root@single1 ~]# cd /test
[root@single1 test]# ll
total 4
-rw-r--r-- 1 root root 16 Jan 18 18:20 video.avi

OK，它又回来了！ 

所以，mount磁盘之前，最好检查下路径下的文件。有用的mv，没用的rm。