Parallel media defect scan in sector read
AssigneeWestern Digital Technologies, Inc.
InventorBaoliang Zhang
Life of this patent
Estimating the term…
Abstract
Systems and methods for performing a defect scan of a disk are provided. In one embodiment, a disk drive comprising a disk, a head configured to read an area of the disk to generate a read signal, and read channel circuitry configured to receive the read signal from the head, perform channel statistic measurements on the read signal, and to generate a Channel Statistic Metric (CSM) flag based on the channel statistic measurements. The disk drive further comprises defect scan circuitry configured to receive the CSM flag from the read channel circuitry, to accumulate the CSM flag to obtain an accumulated CSM flag value and to detect a defect area on the disk based on the accumulated CSM flag value.
Claims19
A disk drive comprising:
- a disk;
- a head configured to read an area of the disk to generate a read signal;
- read channel circuitry configured to receive the read signal from the head, perform channel statistic measurements on the read signal, and to generate a Channel Statistic Metric (CSM) flag based on the channel statistic measurements, the CSM flag being one of a Log Likelihood Ratio (LLR) metric flag and a Viterbi Margin Metric (VMM) flag;
- and
- defect scan circuitry configured to receive the CSM flag from the read channel circuitry, to accumulate the CSM flag to obtain an accumulated CSM flag value and to detect a defect area on the disk based on the accumulated CSM flag value.
A method for performing a defect scan of a disk, comprising:
- reading an area of the disk with a head to generate a read signal;
- performing channel statistic measurements on the read signal;
- generating a Channel Statistic Metric (CSM) flag based on the channel statistic measurements, the CSM flag being one of a Log Likelihood Ratio (LLR) metric flag and a Viterbi Margin Metric (VMM) flag;
- accumulating the CSM flag to obtain an accumulated CSM;
- and
- detecting a defect area on the disk based on the CSM flags.
A disk drive comprising:
- a disk;
- a head configured to read an area of the disk to generate a read signal;
- read channel circuitry configured to receive the read signal from the head, perform channel statistic measurements on the read signal, and to generate a Channel Statistic Metric (CSM) flag by comparing a CSM value based on the channel statistic measurements with a first threshold and outputting the CSM flag to the defect scan circuitry based on the comparison;
- and
- defect scan circuitry configured to receive the CSM flag from the read channel circuitry, the defect scan circuitry including:
- an accumulator configured to accumulate the CSM flag over a moving accumulation window to produce the accumulated CSM flag value;
- and
- a comparator configured to compare the accumulated CSM flag value with a second threshold and to output a defect signal on the disk based on the comparison.
Dependencies are inferred from the claim text.