You might want to look at this - https://en.wikipedia.org/wiki/Disk_cloning and this - https://www.tecmint.com/linux-centos-ubuntu-disk-cloning-backup-using-clonezilla/ - and perhaps even this - Installing Systemback. I used Clonezilla (from a Parted Magic USB) yesterday to clone the entire hard drive (500 Gb) of this old laptop onto a USB connected SSHD and it seems to work flawlessly. Good luck daldude.
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