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part, these snapshots are best when used as a temporary holding area when running 
tests or testing out experimental software before rolling out changes to production 
systems. During Ubuntu's installation process, you were offered the option to create 
an LVM configuration, so, therefore, you can use snapshots to test how security 
updates will affect your server if you used LVM for your root filesystem. If the new 
updates start to cause problems, you can always revert back. When you're done 
testing, you should merge or remove your snapshot.
So, why did I refer to LVM snapshots as a temporary solution and not a backup? 
First, similar to our discussion earlier, backups aren't secure if they are stored on the 
same server that's being backed up. It's always important to save backups off the 
server at least, preferably off-site. But what's worse is that if your snapshot starts 
to use up all available space in your volume group, it can get corrupted and stop 
working. Therefore, this is a feature you would use with caution, just as a means of 
testing something, and then revert back or delete the snapshot when you're done 
experimenting. Don't leave an LVM snapshot hanging around for too long.
When you create a snapshot with LVM, what happens is a new logical volume 
is created that is a clone of the original. Initially, no space is consumed by this 
snapshot. But as you run your server and manipulate files in your volume group, 
the original blocks are copied to the snapshot as you change them, to preserve the 
original logical volume. If you don't keep an eye on usage, you may lose data if you 
aren't careful and the logical volume will fill up.
To show this in an example, the following command will create a snapshot (called 
mysnapshot
) of the 
myvol1
 logical volume:
sudo lvcreate -s -n mysnapshot -L 4g vg-test/myvol1
You should see the following output:
Logical volume "mysnapshot" created.

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Chapter 9