Tuning the encryption!
I have achieved my goal! However I am not still pretty sure about the goodness of the encryption. From my point of view it creates more problems respect the ones it should be solve. If you have a disk failure you may not be able to decrypt that disk, even having a LVM partition spread on several disks may lead to the same problem and if those are also encrypted the risk is even higher.
Today, as a matter of fact, the Solid State Disk (SSD) are lesser prone to get broken as the old spin Hard Drive (HD) and probably this kind of risk is really low respect before; I don't store sensible information on my computers and the risk to get my hardware stolen is presumably lower than get a damaging disk. I believe that my personal data are more on risk while my computer is on internet, if for some reason there is a 0 Day Attack on Linux my data will be grasped whether I have or not my disks encrypted.