[linux-lvm] Understand the snapshot process

[Jean Marie Ariès]

Hi,

I'm using LVM under SuSE Linux 8.0, and I don't understand all the
snapshot process.
I know a snapshot is an exact copy of an existing volume :o)

Our config is :

2 disks 73 Go RAID 1
--> 1 VG "OVG" (60 GB)
--> 1 LV /dev/OVG/data (40 GB) mounted on /share/data

To create a snapshot whith ReiserFS, we do this (I'm following the LVM
How-To) :

Tux :# lvcreate -L30G -s -n snap_admin /dev/OVG/data

and so, we mount the snapshot :

Tux :# mount /dev/OVG/snap_admin /share/snapshot

At this point, the /share/snapshot contain a copy of the /share/data
directory.

The How To say "Do the backup" for exemple with tar.

My question is : Why we must to copy the data with a system command on
the snapshot ? Is a "create snapshot/remove snapshot" not possible ?


Thanks in advnace for your response.


--

Jean Marie Ariès