Partman example using lvm

partman.cfg

d-i partman-auto/disk string /dev/sda
d-i partman-auto/method string lvm
d-i partman-lvm/device_remove_lvm boolean true
d-i partman-lvm/device_remove_lvm_span boolean true
d-i partman-md/device_remove_md boolean true
d-i partman-auto/purge_lvm_from_device boolean true
d-i partman-auto-lvm/new_vg_name string system
d-i partman-lvm/confirm boolean true
d-i partman/alignment string "optimal"
d-i partman-auto-lvm/guided_size string max

d-i partman-auto/expert_recipe string                         \
      boot-root ::                                            \
              128 100 256 ext3                                \
                      $primary{ }                             \
                      $bootable{ }                            \
                      method{ format } format{ }              \
                      use_filesystem{ } filesystem{ ext3 }    \
                      mountpoint{ /boot }                     \
              .                                               \
              1024 100 4096 linux-swap                        \
                      $lvmok{ }                               \
                      lv_name{ swap }                         \
                      method{ swap } format{ }                \
              .                                               \
              4096 100 1000000000 ext4                        \
                      $lvmok{ }                               \
                      lv_name{ root }                         \
                      method{ format } format{ }              \
                      use_filesystem{ } filesystem{ ext4 }    \
                      mountpoint{ / }                         \
              .

d-i partman-lvm/confirm_nooverwrite boolean true
d-i partman/confirm_write_new_label boolean true
d-i partman/choose_partition select finish
d-i partman/confirm boolean true
d-i partman/confirm_nooverwrite boolean true