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Page last updated at 16:20 GMT, Friday, 28 May 2010 17:20 UK

Should you store treasured data on disks?

By David Reid
Reporter, BBC Click

Franck Laloe, French National Centre for Scientific Research
Mr Laloe said CDs meant to last a long time were only good for a few years

Preserving precious data, such as pictures and home videos, on CDs and DVDs could do more damage than good in the end.

That's what the French National Centre for Scientific Research has found out after testing the longevity of the portable media.

"We were surprised to see that the lifetime of discs, some of which were designed to last for centuries, actually rarely lasted longer than five to 10 years," said physicist Franck Laloe.

"In the most severe cases, which were happily quite rare, the data on some discs lasted just one year," he said.

Unlike audio and video tapes that wear out with play, discs are read with a laser so there is no physical contact.

However, the surface which contains more than seven miles of data is deteriorating with age.

Varied quality

French scientists calculated the likely life-span of a disc by artificially aging it with heat, water vapour and light.

CD with damaged edges
Scientists artificially aged CDs with heat, water vapour and light

They found CD quality varied even across the same brand so people willing to pay more for a known name won't necessarily get a better product.

"The brand alone doesn't tell you if you have something that is high or low quality," said Jean-Michel Lambert, from the French National Metrology Laboratory.

"Disc production varies. In the same brand we find discs produced by different manufacturers which means their quality and how long they last for is not necessarily the same," he added.

Also, manufacturers branding discs with their logos could be making the data on them more vulnerable to corruption.

No guarantees

Documentary-makers record about five hundred gigabytes of HD for a 52 minute documentary and need to have a way of storing footage.

Jerome Duc-Mauge, executive producer at Cocottes Minute, keeps rushes stored in a combination of hard drives and data cassettes.

But he still cannot be certain these storage solutions are the best options.

Jerome Duc-Mauge, executive producer at Cocottes Minute
Jerome Duc-Mauge believe there are no guarantees on rushes storage

"This is a big drama, this issue of how long these pictures will last. We don't know. The manufacturer says to us, "Yeah, five years, 10 years, 15 years," he said.

"But we will see in 15 years, we'll see in 20 years if it is still here, or if it has just become a pile of dust at the bottom of the cassette."

There are a few precautions people can take to avoid losing their data. Mr Laloe said these meant being "vigilant".

"Every two or three years, you have to copy your archive onto fresh discs. And after that, because these new discs will last a bit longer, you will have to re-copy them after five or six years," he said.

Mr Lambert recommended spreading digital data rather than keeping it all archived in one place.

"You must have your information in two places at least - on a hard-disc, for example, and on another hard-disc or on a recordable DVD or CD."

Do you have home pictures or videos stored in CDs and DVDs? Would you bother to transfer them to new disks every few years? Or do you already keep them in a variety of places?

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