Measurement and modeling of system-level read-channel performance

摘要

The sector failure-rate performance of a disk drive is a key metric in determining both quality and performance of a disk-drive subsystem. A drive has a sector failure event by either missing a data-synch mark or having an error correction code (ECC) failure caused by too many hard or soft errors for the particular ECC design to handle. Until recently, the sector failure rate was often computed or estimated from the raw bit error rate (BER) of the channel and it was assumed that the error statistics of various read-channel detection schemes were similar enough that a one-to-one correlation existed between the raw BER of a read channel and the sector failure rate of a disk drive. In fact, before the advent of digital PRML read channels, the sector failure rate was often inferred or computed from the measured timing margin (often called phase margin) of a peak detecting read channel.