I need to clone a failing 2TB disk that contains a NTFS partition, using Debian GNU/Linux. The disk has a number of non-relocatable bad sectors, so I know that part of the data is already lost; however I need to clone the the disk in order to try to recover the rest using testdisk
.
The command I issued to clone it is:
dd if=/dev/sdc of=/dev/md2 bs=512 conv=noerror status=progress
and it took about 2 days to complete, during which it found bad sectors at about 3GB, 66GB and 88GB. The failing disk is quite old and it isn't Advanced Format, so I know its sectors are 512 bytes each for sure.
The problem is that trying testdisk /dev/sdc
it reads the directory (but then fails to recover the files, because of bad sectors), while tryng testdisk /dev/md2
does not even list the directory contents. The disk contains only the NTFS partition, that spans the whole available space. Why the clone is not the same as the original, at least on the sectors that aren't damaged? Am I cloning in a bad way and I should clone it some other way, e.g. different command or options?