I want to create a bit-by-bit backup of my DVD and a Blu-ray disc without removing its encryption. Is dd be the best method, and if so, what flags or settings should I use? Also, is comparing the SHA-256 hash of the generated ISO file with the hash of the original disc’s raw data (read from /dev/sr0) the best method for verifying the backup’s integrity?
I’d recommend ddrescue over dd for optical media backups only because if you’ve got bad blocks it will try them again at a different speed/angle
Does
ddrescuestill check every sector even if there are no bad blocks? I’m worried it might just copy sectors without verifying, which could mean the backup isn’t a perfect copy.It’s just dd with extra flags enabled for data recovery.