priusz wrote:So I think the only working method is the one I linked, or maybe
I already mentioned another working method - Acronis TrueImage - which I believe will suit the OP better.
Plus, I note you are still giving your "output.iso" file a ".iso" extension in your example. That is a bad habit to get into when the file is not actually an ISO container. Better in that case to call it "output.raw".
The dd suggestion btw involves an image file equal in size to the disk being copied - which is far inferior to the Acronis method, which only copies used clusters, and
it compresses them to save time and space. For example the last Acronis backup I took of the C: drive on the PC I'm using right now... is 19GB, and took about 15 minutes to create. That time is very good, and the file size is manageable. A dd image of the same drive would have taken considerably longer, and would have been 230GB... somewhat less manageable. There may indeed be some parallel universe in which dd is preferable to Acronis, but it isn't the universe I inhabit!