On Fri, 12 Sep 2003, Volker Kuhlmann wrote: ... > Carl's MO drive is no doubt convenient now, but that says little about > longevity. Durability of the media is only one factor which needs to be ...
MO drives and cheap CD writers are made for different markets. While MO drives target professional use cases (and are accordingly priced), cheap CD writers and CD-R media are clearly consumer products where affordability weighs more than quality. Then the technologies of MO and CD-R have some significant differences. MO drives work in principle like a harddisk, except that they use a magneto-optic write/read technique instead of a purely magnetic one. This means that MO disks are formatted in cylinders and sectors like a HD, and bad sectors can be marked as bad and will then not be used. Consequently, there should be no errors on the good sectors. Should there be any, then there still would be the possibility of either detecting or correcting them. In contrast to that, when a CD-R is written, the bitstream to be written is written without having a priori information about the quality of the actual medium. To overcome local media impurities, and also scratches on the surface, the data are protected by a rather long error-correcting code. This means that read errors of individual raw bits on a CD are accepted as inevitable. The error correction can deal with them up to a certain limit... My personal statistics: I have been using an Olympus MO drive with 230 MB for eight years without any single incident of read failure. I never had to replace any of the media. Of the CD-Rs I have written, between 2 and 3 percent cannot be read any more (even trying different drives on different computers) after a period of two to three years. Kind regards, Helmut Walle. +----------------+ | Helmut Walle | | [EMAIL PROTECTED] | | 03 - 388 39 54 | +----------------+
