For long term investment, it's good to have a bigger HDD. I read from a computer magazine about optical media have short life span.People & manufacturer believe it can last for ever (perhaps at least 50 years or maybe more).Eventually, the media itself degrading.

I confirm it by myself by checking my anime which I save in few years back.I just kept it in the box only.Apparently that CD cannot be played properly (imation beb ...how come huh ?).Try recover using ISObuster but failed.

It been suggested to do backup on optical media for every 2 or three years.Or maybe every years.

Just a thought & experience to share.