The DVD is a medium similar to the CD since its dimensions are the same (a 120 mm diameter disc or a mini 80 mm version) and its operating method is similar. However, there are technical differences concerning, on one hand, the density / storage-recording capacity and, on the other hand, the processes and digital treatments (software) used for their backup.
Data recording is performed by the effect of the laser’s heat on the surface of the DVD. Their capacity depends on the type of DVD but can reach up to 8.5 GB.
The DVD has a multilayer structure composed of polymers and organic dyes, which makes it vulnerable to chemical aging, light, high temperatures, and humidity.
The National Laboratory for Metrology and Testing (LNE) demonstrated that 17% of discs show degraded areas after 7 years, even when stored under good conditions, with 12% irreversible data loss. Even DVDs labeled “archive”, “Milleniata”, or “Gold” did not show the best results. Rewritable discs (DVD+/-RW) are twice less resistant to aging. See the study
The burning speed allows a transfer rate of up to 64.8 MB/s (x48), but a burn speed that is too high has an impact on the lifespan of the medium. With the same reference, better results are obtained when burning at 50%.
The low capacity, the long burning time compared to a hard drive, and the weak long-term lifespan make this medium impractical and not very secure. It is now being replaced by Blu-ray, whose lifespan appears equivalent but which has a higher capacity.
In term of security, here is no mechanism to secure the data. You must use third-party software to protect your files.
Longevity and reliability
Accessibility and practicality
Transfer speed
Security
Price/GB