LVM and Raid1 with different size physical volumes

[turtles]

How does LVM and Raid1 work with different size physical volumes in one volume group (VG)?
For example I have two matching drives in a VG, one has just one LVM partition the other has a few small partitions along with the big LVM one so they are not identical but close.
I have one Logical Volume I am installing Gentoo on I gave it a chunk of space.
But how to I allocate the rest of the space without wasting any?
with

[Akashchauhan]

LVM with RAID1 will mirror the LV across both drives and use the smallest available space. It would be better to create or allocate other logical volumes so that both drives fit well.