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Caution: files put on DVD, USB memory chips break after a few years of use?

2, 25. 2008

   Many people try to keep important files for a long time by digitalizing them. But the matter is not all that easy. It is wrong to believe that files can be stored for ever. In case of DVD's, there are differences in "memory life" depending on their makers. The condition is said to be the same about USB memory sticks which are popularly used.

   Since the CD was first started to be used, it has rather been known to the users that anything burned on the disc would deteriorate with years. This problem seems to remain the same with the DVD for which demand is likely to grow in the future for storing videos.

Some DVD's declared "life expired" while brand new

News-site showing the life expiration of a USB memory stick
News-site showing the life expiration of a USB memory stick

   According to a study conducted by the Digital Content Association of Japan between 2003 and 2006, the life of DVD's greatly differs depending on their makers. Tests were conducted on the products of Japanese and foreign brand names under high temperature environment in which they tend to deteriorate quicker. The test showed that the products of some brand names showed no sign of deterioration and guaranteed as "no life expiration." Some others, however, were found to show error messages even before the tests were started on them, and they were classified as "brand new but their life expired."

   To keep what is burned to the disc, therefore, it is not enough to take a good care of the disc, such as "not exposing to the sunlight," but the makers of the discs have to be carefully selected.

   The problem of the "life span" may be applied also to the USB memory sticks, which are now widely used as memory media. The USB memory sticks are made of semiconductor device, and there is a limit to the number of times data can be written on them. When the data can not be written to the stick, therefore, that is the end of its life.

   The blog-form news-site, GIGAZINE, posted on Feb. 4 an article that reported in detail the moment when the "life" of a USB memory stick ends. According to the article on the site, an error occurred when a ZIP-format file was put back from a USB memory stick to the HDD of a PC and was decompressed, resulting in distorted picture.

Life does not end in a year or two in ordinary use

   What would be the life span of a USB memory stick in general? This question was put to Buffalo, maker of USB memory sticks that holds the largest market share (not the maker of the sticks mentioned in the GIGAZINE article). About the "life span," the sales promotion group of the company said:

There is a difference in the number of times data can be written to the sticks depending on the type of the sticks. So there is no one answer to cover all of them. But usually, "we think in terms of hundreds of thousands of times."

   So there is no decisive life span for all of the memory sticks. Supposing, however, that data can be written on a stick 10,000 times and it is accessed five times a day, its life span should come out to be almost five and half years. The group also said:

The life should not expire in one year or two in ordinary use.

   And if the stick is used beyond the life span, the group said:

The file shouldn't be distorted immediately. But if the stick is put under a stress (such as sudden rush of accesses), it might occur that the stick is unable to read.

   The USB memory stick that was declared "life expired" in the GOGAZINE article was found out to be in such a condition only 10 and half months after it was purchased. It was used only once or so in every two or three weeks. According to the article, the stick was judged to be "simple break-down," instead of "life expiration," and it was sent for repair.

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