I tried to backup my partition using dd on another disk and I created a partition of the same size.
When I finished the copy I had problems mounting the partition since I got
bad geometry: block count .
I noticed that in order to create a correct backup (avoid bad geometry error) not only the two partitions must have the same size in MB but also the same number of blocks (The number in blocks you can check using fdisk -l). I also noticed that the number of blocks varies if I create the partition starting from the beginning or starting from the end . Can someone explain me the behaviour and how to create two partition with the exact the same block size?