root@ubuntu:~# mount /dev/mapper/vgubuntu-root /mnt
root@ubuntu:~# mount /dev/sda3 /mnt/boot
root@ubuntu:~# mount -o rbind /dev /mnt/dev
root@ubuntu:~# mount -t proc proc /mnt/proc
root@ubuntu:~# mount -t sysfs sys /mnt/sys
root@ubuntu:~# cp /etc/resolv.conf /mnt/etc/resolv.conf
root@ubuntu:~# chroot /mnt /bin/bash
root@ubuntu:/# apt-get install cryptsetup lvm2
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following extra packages will be installed:
  watershed
Suggested packages:
  busybox
The following NEW packages will be installed:
  cryptsetup lvm2 watershed
0 upgraded, 3 newly installed, 0 to remove and 369 not upgraded.
Need to get 543 kB of archives.
After this operation, 1,835 kB of additional disk space will be used.
Do you want to continue [Y/n]? Y
Get:1 http://de.archive.ubuntu.com/ubuntu/ oneiric/main cryptsetup amd64 2:1.1.3-4ubuntu2 [121 kB]
Get:2 http://de.archive.ubuntu.com/ubuntu/ oneiric/main watershed amd64 5 [11.5 kB]
Get:3 http://de.archive.ubuntu.com/ubuntu/ oneiric/main lvm2 amd64 2.02.66-4ubuntu3 [410 kB]
Fetched 543 kB in 0s (609 kB/s)
Selecting previously deselected package cryptsetup.
(Reading database ... 126698 files and directories currently installed.)
Unpacking cryptsetup (from .../cryptsetup_2%3a1.1.3-4ubuntu2_amd64.deb) ...
Selecting previously deselected package watershed.
Unpacking watershed (from .../archives/watershed_5_amd64.deb) ...
Selecting previously deselected package lvm2.
Unpacking lvm2 (from .../lvm2_2.02.66-4ubuntu3_amd64.deb) ...
Processing triggers for ureadahead ...
Processing triggers for man-db ...
Setting up cryptsetup (2:1.1.3-4ubuntu2) ...
update-initramfs: deferring update (trigger activated)
Setting up watershed (5) ...
update-initramfs: deferring update (trigger activated)
Setting up lvm2 (2.02.66-4ubuntu3) ...
update-initramfs: deferring update (trigger activated)
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.img-3.0.0-12-generic
cryptsetup: WARNING: invalid line in /etc/crypttab -