[linux-lvm] Snapshot Info

[James Pattinson]

Hi

OK, I've got snapshots working now that I've re-created my PVs with beta8
tools.

Where can I find some more info about how snapshots work? I'm a bit
confused as to how space is allocated. Here's an example of what I'm
seeing:

I have a 3GB LV called /dev/vg00/lvol6 that is about half full.

1.	Created a 512MB snapshot LV for this LV
2.	Copied 9MB worth of data to /dev/vg00/lvol6
3.	Looked at lvdisplay /dev/vg00/snap_lvol6 and 18MB is used in the
snapshot.

Where does the figure 18MB come from? is the fact that it is 2 x 9MB
significant?

I'd quite like to know how big I should be making my snapshots.

Cheers!!

James