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I burned an Ubuntu 10.04 ISO to a CD-R (using the slowest speed there was in the software) only little over a month ago. I just checked the md5 now and found out that the disc had become corrupt. The disc hadn't been exposed to sunlight, or kept in a humid place, or been hit or dropped. I had only used it once for installation and that was it - put it in its case and kept it "safe" (or so I had thought). And the disc wasn't really the cheapest either. So what is it that could/does cause corruption to CD's within such short time?

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Was the disc checked before and was the MD5 then OK? Did you use the disc with a different optical drive? Some drives might have problems with certain CD-R media, so it could be that one drive reads fine and the others gives errors. – Roalt Nov 21 '10 at 15:16
Yes, I checked the md5 right after burning to make sure I had a good disc, and only then went ahead with installing from it. But no, I have not used a second drive to cross-check the current state. Nevertheless, since it is this very drive that I had used to burn the disc, and also to check it the first time, it is highly unlikely that the apparent corruption is an error on the drive's part. – Mussnoon Nov 21 '10 at 17:17

The problem is material degradation. 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.

"Many of the cheap burnable CDs available at discount stores have a life span of around two years," Gerecke says. "Some of the better-quality discs offer a longer life span, of a maximum of five years."

-- From PCW

The lifetime of many articles follows a bell-curve, so if the average is 2 years, in a large enough sample you'll find one that lasts a month.

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Thanks for the prompt response. Right next to the CD in question, there's another that I burned way back in 2006 and have been storing in similar conditions, and it still works flawlessly today. – Mussnoon Nov 21 '10 at 10:37
Eight years ago I moved into a brand new office, it had 64 fluorescent light tubes in the ceiling, all installed the same day. Same make, same batch. They all turn on together, the temperature and other conditions are identical. One fails every two weeks or so, about half are still running. So the lifetime varies from a few weeks to eight years. You are probably just unlucky with that CD. – RedGrittyBrick Nov 21 '10 at 10:44

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