Stock Ubuntu pre-seed file.
From https://help.ubuntu.com/lts/installation-guide/example-preseed.txt
Slim down Ubuntu netboot file structure. Use Syslinux 4.05's menu.c32 instead of vesamenu.c32.
Create net-console preseed file and pxe conf file.
Create LVM atomic preseed file.
Create 4x2TB RAID6 LVM custom-root preseed file.