Perfect! Thanks!

Sadly I cannot extend the filesystem anyway thanks to the installer defaulting to ext3 so I'm using lvm for almost nothing except snapshots (i.e. I shouldn't be needing lvcreate/lvextend).

What I was worried was: my fs is definetely on the HW raid (logically), but I wasn't sure if free blocks would have come from somewhere else.

Anyway this seems to do the trick. Thanks once again.

Wallace