Back Up your CD

Nowadays people always save their data (computer) in CD or DVD or maybe in the harddisk. If you save it in the CD, just make a back up every 5 years, if not your data will be broken or lost.
Oh ya if your quality of CD is bad (the cheaper ones), you have to make back up less than 5 years, you have to check it every 2 years, to avoid losing data.
About DVD, hmm it same with CD i think...