I have once cloned my hard disk to a brand new SSD of the same size by using a dd command.
sudo dd if=/dev/sda of=/dev/sdb bs=4K status=progress
In my case it took 3,5 hours and it was successful. But beware not to make an error on the cloning direction!
The if= and of= designations were taken from the results of
sudo blkid
and I did it all with a system booted from a USB stick, because I wanted to be sure that neither the installed hard disk nor the installed SSD are mounted. None of the two file systems were mounted during this cloning operation. The number of sectors of the source and target were indentical.
If they differ, one would first have to re-size partitions on the source drive and then move partitions on the source device such that to be used content becomes consecutive (but there may be empty space within the partitions). It all has to fit to the target device.
The disadvantage of this approach is, that the partitions on the cloned hard disk have exactly the same UUIDs, and DiskLabels and so on as the original hard disk. On one hand this ist very good, because all references within the disks remain consistent. But on the other hand, having disks with identical UUIDs and DiskLabels bears much potential for destroying the content on the original hard disk and on its cloned image on the SSD!
Therefore I shut down the computer immediately after this cloning operation and physically removed the hard drive from it.
My hard disk originally had a swap partition (which actually does not make sense on a SSD). I re-sized other partitions to regain this space of the SSD later. Unfortunately I did not write down, how I achieved this step.
