Good practices for backups on DVD

DVDs are good and cheap media for middle term backups of old files, or periodical snapshots that fit into 4.37 GiB space. Best example of mine is storing old photos.

Choose you disc

Choose good quality discs from known brand/manufacturer relying on reliability statistics

Choose DVD+R over DVD-R - +R uses better writing method and has better error correction, check this article for long explanation. Do not use rewritable discs that use erasable data layer, that could be more easily damaged.

Burning speed - the lower the best - higher speed means potentially more errors to correct during writing and reading. Most hardcore safe backup setting will be x1 , but 4x or 8x should be quite safe when today DVD writers give you x16 writing speed.

Handling

DVDs are fragile to physical damages, specially vulnerable to scratches. So discs should be handled with care, without touching recorded surface. Discs surface should be clean to avoid scratching by hard dust particles. Blank discs should be perfect clean before writing, as any speck on surface will block laser beam.

Do not place adhesive labels and use special CD/DVD markers for labeling. The best place for tiny label is not recordable small middle ring. Why is that? Label side of CD or DVD is separated only by thin layer, that chemicals could easy get through and damage data layer with recorded pits.

Recorder DVDs should be stored in dark and dry place. Here is nice list of DVD handling recommendations on a NIST page.

Additional backup safety measures

Redundancy increases probability of data retrieval. For critical data it makes sense to make more copies. Other copy could be placed off-site, for better protection in fire and flood proof place.

Another option would be additional error correction data created by ECC software like dvdisaster. The best option is to write additional ECC data scattered on the same disc with data. It's a trade-off of disc capacity for additional data safety.

Every media has limited life span even stored in best conditions. Some manufacturers give even 30 years (or even 100 years!) for DVD discs, but I'm not such optimistic. Stored archives should be periodically checked for errors (dvdisaster has that functionality), and then moved to new media. It makes also sense in case of technology change and migration. Today next popular optical format is Blu-Ray Disc, but its still young.