I have been having a painful time trying to automate an Ubuntu 14.04 Server Installation with RAID 1 partitioning. I'm testing this on top of VirtualBox with two Virtual Disk Images (dynamically allocated to increase in size up to 1TB) and a custom ISO that I am generating from the preseed.
I'm trying to have a RAID 1 that mirrors two hard disks such that the first 32GB of BOTH 1TB disks is "swap" and the rest of the disk is ext4. i.e. md0 = sda1 and sdb1 (swap) md1 = sda2 and sdb2 (ext4). The problem, however, is that every time I try to do this, I get stuck at the "Partition Disks" manual installation menu and only the sda partition information has been populated (i.e. it will show the swap and ext4). The sdb partition will be empty and I will have to manually enter the information and generate the partition table from there. I have tried a wide variety of preseed configurations found online, tinkered with them, and still have had no luck. Any advice / help is greatly appreciated! Note: I have used kickstart to surpass some of the initial menus, not sure if this could have interfered somehow.