Analysis of Asymmetric Deterministic Bitshift Errors in a Hard Disk File

An extensive statistical analysis has been made of soft errors occurring in an IBM 3380K hard disk file. About 90% of the errors were bitshift induced involving a single bit. There was a high degree of early/late asymmetry. Decreasing system signal-to-noise ratio (S/N) increases the error rate, but reduces the early/late asymmetry. The repeatability of errors suggests that most errors happen at or near a media-defect site. This paper will present both the method of analysis and the experimental results. In addition, self-consistent write process modeling, taking into account media defects, indicates bitshift and amplitude degradation commensurate with the experimental results. © 1990 IEEE