[linux-lvm] Newbie to snapshot

[armani]

Hello List

I am a newbie to use LVM.

When I read the HowTo on
http://www.linux.org/docs/ldp/howto/LVM-HOWTO/snapshots_backup.html
I tried to practice it with my Linux Box.

Everything is fine but snapshot !

==============================================================
[root at met tmp]# lvscan
lvscan -- ACTIVE   Original "/dev/Vol1/LV1" [10 GB]
lvscan -- ACTIVE            "/dev/Vol1/LV2" [2 GB]
lvscan -- ACTIVE            "/dev/Vol1/LV3" [2 GB]
lvscan -- ACTIVE            "/dev/Vol1/LV4" [2 GB]
lvscan -- ACTIVE   Snapshot "/dev/Vol1/snapshot" [1.97 GB] of /dev/Vol1/LV1
lvscan -- 5 logical volumes with 17.97 GB total in 1 volume group
lvscan -- 5 active logical volumes
==============================================================

As the description, I make a Original LV device named /dev/Vol1/LV1,
and then I make a snapshot device named "/dev/Vol1/snapshot" for
/dev/Vol1/LV1 .
So I try to put something for /dev/Vol1/LV1

# mount /dev/Vol1/LV1 /mnt/LV1
# mount /dev/Vol1/snapshot /mnt/snapshot [ I'm using ext3 ]
# dd if=/dev/zero of=/mnt/LV1/test bs=1M count=10

and then
# tar cf /dev/hda8 /mnt/snapshot or # tar cf /tmp/test.tar /mnt/snapshot
but I can't see any file except the "/mnt/snapshot/lost+found" directory
with the following command !!
# tar xf /dev/hda8 or # tar xf /tmp/test.tar

I don't have any idea to use this snapshot, any suggested references ?