Burning digital photos to CDs is currently the most common thing to do for digital photographers to back up their photos. But according to Kurt Gerecke, a physicist and storage expert at IBM Deutschland, this method is not recommended as many of the cheap burnable CDs available have a life span of around 2 years.
He says, ” Optical discs commonly used for burning, such as CD-R and CD-RW, have a recording surface consisting of a layer of dye that can be modified by heat to store data. The degradation process can result in the data “shifting” on the surface and thus becoming unreadable to the laser beam”
Similar situations are also applied for hard disks. The problem not so much the disk itself as it is the disk bearing, which has a positioning function similar to a ball bearing. Hard Disk with 7200 rpm is recommended if you want your photos last longer.