Once you have decided to encrypt your hard drive, you might find yourself in the situation where you need to pull off data from it when the regular decryption mechanisms you use are not in place. E.g. when the OS is not booting or the drive has some physical problems. In that case you need to boot from a CD/DVD that supports the encryption technology that you used. In my case I need a live Ubuntu CD/DVD, preferably the same version that was used to encrypt the disk! Otherwise there might be incompatibilities:
sudo apt-get install lvm2 cryptsetup
sudo modprobe dm-crypt
sudo cryptsetup luksOpen /dev/sda2 crypt1 (result: key slot0 unlocked, command successful)
sudo vgscan --mknodes (result: Found volume group "default")
sudo vgchange -ay (logical volumes become active)
sudo mkdir /volume1, etc.
sudo mount /dev/default/root1 /volume1