software raid and lvm in preseed

[Jin Zhao <jzhao@qcorps.com>]

Where are instructions for that in preseed install? I searched email 
lists and installer manual but all examples found so far use physical 
disk as partman examples. I also tried manually install and set up 
software raid, but the 'debconf-get-selections --installer' output 
contains no valuable information of how partman setup and use md devices.

If anybody has done software raid or lvm install in preseed, please give 
shed some lights on it.

Thanks,

Jin