Abstract :
ICI has developed a unique and novel method of certifying a Terabyte optical tape. The tape quality is guaranteed as a statistical upper limit on the probability of uncorrectable errors. This is called the corrected byte error rate (CBER). The author developed this probabilistic method because of two reasons why error rate cannot be measured directly. Firstly, written data is indelible, so one cannot employ write/read tests such as used for magnetic tape. Secondly, the anticipated error rates need impractically large samples to measure accurately. For example, a rate of 1E-12 implies only one error per tape. Nevertheless, customers expect performance predictions which are supported by practical test results. The paper describes the mathematical basis, measurement apparatus and applicability of the method
