In 1994 there was an article in the British music journal The Wire claiming compact discs would have a life of about ten years, references to the article appeared in in Scientific American making. Problem with that is that you only need to talk to a few friends who will happily inform you that they have had their CD of ___ fill in the blank for 12years or more. But another poll of friends is bound to find one or two who have tried to read back data from relatively young CDs and failed. As a rule manufacturers will claim their products will be usable for something like 100 years. A figure some have suggested has more to do with the fact that in a hundred years no one will be around to contest the assertion. Sceptics say 5 to 10 years is more like it but that lifespan may have more to do with substandard disks in which the aluminium oxidized after a short time. But again this will depend on use. A disk accessed daily will fail faster than one accessed monthly or even yearly.
Let’s have a look at the two most common kinds of disk.
The modern Compact Disc-Read Only Memory (CD-ROM), is a type of optical disk capable of storing large amounts of data – up to 1GB (gigabyte) the large capacity version tend to be expensive while the most common size is 650MB approximately sized version can be found in any supermarket or many other outlets. To give some idea of capacity a single CD should be able to store around 300,000 text pages.
Digital Versatile Disc (DVD) is a type of optical disk technology and is the go to format for most films (high definition is changing this) DVD can also be used to store data. For reference a DVD can store about 1,400,000 text pages.
CD-Recordable and DVD-R can be recorded once, after which the disc becomes read-only.
CD-RW/DVD-RW are Re-Writable.RW discs can be written to multiple times but the film layer on RW discs breaks down faster rate than CD-R/DVD-R discs, especially with frequent recording and re-writing.
What this proves is that as a long term storage medium, CDs and DVDs are not your best option, but CD and DVD can provide a solution for data which in theory at least could be safe for around a decade and if you are looking for safer could be a stop gap in your data storage strategy.
Next time I’ll be looking at USB storage.