mount挂载硬盘出错mount you must specify the filesystem type lvm？

我的机器两个硬盘,一个80g的做的lvm 是我从别的机器上拿下来的,上面有数据.我想在我现在的系统上挂载它,可不行,高人给点指点!!!!!!
[root@all /]# fdisk -l
Disk /dev/hdc: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hdc1   *         1        13    104391   83  Linux
/dev/hdc2            14      9729  78043770   8e  Linux LVM

Disk /dev/hda: 40.0 GB, 40020664320 bytes
255 heads, 63 sectors/track, 4865 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hda1   *         1       255   2048256   83  Linux
/dev/hda2           256      3934  29551567+  83  Linux
/dev/hda3          3935      4444   4096575   83  Linux
/dev/hda4          4445      4865   3381682+   f  Win95 Ext'd (LBA)
/dev/hda5          4445      4699   2048256   83  Linux
/dev/hda6          4700      4801    819283+  83  Linux
/dev/hda7          4802      4865    514048+  82  Linux swap
[root@all /]# mount /dev/hdc2  /mnt/cdrom
mount: you must specify the filesystem type
mount 时出线上面的错误!谁给点提示!谢谢!

回答：

1.先用vgscan 
2.vgchange -ay
3.lvscan
4.mount

到第三步的时候如果正常会显示出两块硬盘的lv状态都是active，此时再

#mount -t ext3 /dev/VGname/LVname /mnt/cdrom

就可以成功了。

来自 http://blog.csdn.net/qiudakun/article/details/5336754