So I have a 16tb raid6 on one of a new batch of machines I am setting up. I will be using LVM on top of this and am wondering if there are any compelling reasons to break the raid up into partitions first or any compelling reasons not to.
I know that if I want to use different volume groups in lvm I'll need different physical volumes... but I don't know if that really matters a whole lot here.
The OS is installed on a separate 2tb raid1.
No, one big partition will do just fine and most accurately represent the underlying disk to LVM.
Your limitation comes from the filesystem, if you are putting ext4 on it, you'll be fine, as the largest filesystem that can cope with is 16 TiB