Why burn non-rewritable optical discs? Optical discs are some of the few storage mediums that cannot be attacked by ransomware. Useful when running a company holding data that one would pay lots of money to get back. If you store the discs in a fireproof safe right after burning them and use plain readers for accessing the content, it will be physically impossible for a virus to destroy your backups even if they manage to steer the laser's arm manually at firmware level or short an H-bridge to start a fire. A class 1 laser meant for reading won't do much damage even if it stops spinning. You still need protection against spyware, but at least you won't have to pay the criminals. Blurays have more scratch resistance, but CDs are more fault tolerant against cheap readers and wobbly arms in laptops when you don't have so much data anyway. Best to keep your important paperwork on CDs and the lesser important larger files on DVD/Bluray.