archiving software
Out of context: Reply #14
- Started
- Last post
- 14 Responses
- tymeframe0
i'm relying on CDs and DVDs....1 HDs can crash, 2 the data isn't locked so the files can become corrupt.
I found this off google.
CD-R, DVD-R, DVD+R Discs
Most tests of optical disc life expectancy are performed with recordable discs (CD-R, DVD-R, DVD+R). The tests are generally performed by manufacturers, and the discs are usually categorized by the metal and dye types used in the disc. These discs use gold, silver, or a silver alloy for the reflective layer instead of aluminum as in ROM discs. Gold will not corrode but is expensive. Silver is more reflective and cheaper than gold but is susceptible to corrosion if exposed to sulfur dioxide, an air pollutant that can penetrate the disc in the same way oxygen can—with moisture. Manufacturers use various silver alloys to help inhibit silver corrosion, and most R discs available today use a silver alloy reflective layer. The chance of silver corrosion from exposure to sulfur dioxide is less than the chance of aluminum oxidation caused by high humidity. Nonetheless, keeping the disc in a filtered "clean air" environment can minimize or eliminate its exposure to sulfur dioxide. With proper storage, these discs will outlast the technology.
R discs use a dye-based layer (organic dye) for recording data. These are "write-once" discs and cannot be erased by CD or DVD drives. The organic dye used in the data layer of R discs degrades naturally but slowly over time. High temperatures and humidity will accelerate the process. Prolonged exposure to UV light can degrade the dye properties and eventually make the data unreadable. Heat buildup within the disc, caused by sunlight or close proximity to heated light sources, will also accelerate dye degradation.
Manufacturers claim that CD-R and DVD-R discs have a shelf life of 5 to 10 years before recording, but no expiration dates are indicated on CD-R, DVD-R, or DVD+R packaging, nor are there published reports of tests to verify these claims. Still, it would be prudent, in light of these claims, to purchase new discs as they are needed rather than to order large quantities and stockpile them for future use.