Upgrade from 11.10 to 12.04 using alternative CD

[tiger2000]

Hello

I decided (finally !!) upgrade from 11.10 to 12.04. But, I have to consider that I use LVM with encrypted disks and I found
a question about issues during upgrade.
http://askubuntu.com/questions/139401/failed-upgrade-from-11-10-to-12-04-on-an-encrypted-filesystem.
It seems , per the link, that I would be able to solve the issues.. however, I am not sure and I really do not want to spend a week to do upgrade without access to my data.

So, my guess is that I can upgrade from alternative CD - 12.04.4.
My questions are :
1) Am I able to upgrade using the alternative CD ? (My guess is that the installation process is able to identify that the computer (desktop) already has a Linux installation and
can suggest me to only upgrade, but I am not sure).
Please , provide comments

2) If I decide install from scratch, should I be able to keep my LVM untouched , at least /home ?


thanks in advance

[sudodus]

I'm afraid it makes it harder to succeed upgrading with LVM and encrypted disks. So it is very important that you make a cloned copy (full copy or compressed image) of your present 11.10 system or at the very least backup all personal data (pictures, documents ...).