d-i     partman-auto/disk string /dev/sda /dev/sdb
d-i     partman-auto/method string raid
d-i     partman-lvm/device_remove_lvm boolean true
d-i     partman-md/device_remove_md boolean true
d-i     partman-lvm/confirm boolean true
d-i     partman-auto/choose_recipe select boot-root
d-i     partman-auto-lvm/new_vg_name string vg00
d-i     partman-auto-lvm/guided_size string 100%
d-i     partman-auto/expert_recipe string        \
           boot-root ::                          \
             1024 30 1024 raid                   \
                $lvmignore{ }                    \
                $primary{ } method{ raid }       \
             .                                   \
             1000 35 100000000 raid              \
                $lvmignore{ }                    \
                $primary{ } method{ raid }       \
             .                                   \
             80000 100000000 100000000 ext4             \
                $defaultignore{ }                \
                $lvmok{ }                        \
                lv_name{ root }                  \
                method{ format }                 \
                format{ }                        \
                use_filesystem{ }                \
                filesystem{ ext4 }               \
                mountpoint{ / }                  \
             .                                   \
             8000 60 8000 swap                   \
                $defaultignore{ }                \
                $lvmok{ }                        \
                lv_name{ swap }                  \
                method{ swap }                   \
                format{ }                        \
            .

# Last you need to specify how the previously defined partitions will be
# used in the RAID setup. Remember to use the correct partition numbers
# for logical partitions. RAID levels 0, 1, 5, 6 and 10 are supported;
# devices are separated using "#".
# Parameters are:
# <raidtype> <devcount> <sparecount> <fstype> <mountpoint> \
#          <devices> <sparedevices>

d-i partman-auto-raid/recipe string \
    1 2 0 ext2 /boot                \
          /dev/sda1#/dev/sdb1       \
    .                               \
    1 2 0 lvm -                     \
          /dev/sda2#/dev/sdb2       \
    .
d-i     mdadm/boot_degraded boolean false
d-i     partman-md/confirm boolean true
d-i     partman-partitioning/confirm_write_new_label boolean true
d-i     partman/choose_partition select Finish partitioning and write changes to disk
d-i     partman/confirm boolean true
d-i     partman-md/confirm_nooverwrite  boolean true
d-i     partman/confirm_nooverwrite boolean true