How to add another disk into the root of the encrypted Ubuntu

Manipulation with encrypted root (/) partition of your Ubuntu is not exactly a seamless task which you would like to do everyday. There is one special case which can’t be covered by standard documentation. You can find tutorials and documentation for expanding your root partition even when it’s encrypted, but in my case, I had to add a new hard drive to expand it with a new space. If you have installed your encrypted Ubuntu without any custom changes during the installation process, it is installed in LVM which is in encrypted partition of your hard drive. »