About SnapShot

[Vahric MUHTARYAN]

Hi Everybody , 
 
            Today I try to learn snapshot with FreeBSD 5.4 , perfect it's
working very fest . I wonder something if somebody have knowledge about
snapshot or have a documentation about it I will be happy. 
 
First I don't understand How system can take snapshot quickly I tried it on
new installed freebsd 5.4 and when I gave a command on console snapshot file
created in a second which 256MB , I wonder How fast will be on bigger
partitions. Anybody know How snapshot tecnology is working ? Because it's
creating an single file and it's 256 mb , it's not possible to copy /var
folder to another folder in a second ... 
 
Second Why I can't create snapshot file on different directory , I tried to
linking but it didn't work ! 
 
And anyway Does it possible to back from snapshot file to original portion
... I mean snapshot is creating only one file When I want to backI have to
mount it to system and copy back files Im asking without copying something
and mouting snapshot file can I make a restore ? 
 
Thanks Everybody  
    
Regards
            Vahric