Is it possible to use free space of a partition mounted on
/ as volume group?
I mean creating VG on that free space, does it cause any problem?
If that is the case, you cannot use the 489.8 GB as disk for your volume group.
However, if this is the case
Then I can use the 399.8 GB to create a PV in LVM and add that PV to a VG.
EDIT: Well, actually you could
I just came to think of something after I posted the answer. I was wondering if you could use loop interfaces with LVM. And it turns out you can. I am right now booting up a test box to play a little with that. I will edit this to be the results after I'm done.
EDIT: Actually - you can do it
This is basically how I did:
And I ended up with
So, technically yes. You can do that. I would still advice you not to, though. I use LVM for all my disk.
I cannot set up the loop interfaces until my LVM has started - but when LVM starts, it cannot find the loop devices. So, I would have to do it manually at all times.