[linux-lvm] snapshot size

["Barry, Christopher" <cbarry infiniconsys com>]

Hi All,
	I just got LVM2 w/XFS up and running recently. I rsync'd all of my existing home data into a new lv, and decided to test the snapshotting functionality. I had tested with a dd'd test file in a test lv prior to this, and all looked good. Now, I have a 110G lv with all of my home data in it. I create a snapshot lv (takes under 10 seconds!) of home without error, and I can mount the snapshot lv, and 'ls' it, poke around in it, and it *looks* like all is there. However, a df shows the snapshot volume to be only ~32G vs 110G for the original.

Q: Is this normal? Is the snap just way more space efficient?
Q: Also, how does the snapshot work so fast??

Thanks for all of your help,

--
Christopher Barry
Manager of Information Systems
InfiniCon Systems
http://www.infiniconsys.com