http://phaq.phunsites.net/2014/08/03/enable-software-raid-on-xenserver-6-2/
wget -qO- http://phunsites.net/scripts/x6raidsetup.sh.gz | gunzip | bash
After reboot
sgdisk --new=3:16779264:1000215182 /dev/sda
sgdisk --typecode=3:fd00 /dev/sda
mdadm --manage /dev/md0 --add /dev/sda1
mdadm --manage /dev/md1 --add /dev/sda2
mdadm --manage /dev/md2 --add /dev/sda3
xe sr-create content-type=user device-config:device=/dev/md2 name-label="Local Storage" shared=false type=lvm