Data storage device screening heads by verifying defects after defect scan
View Patent ↗A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks. A defect scan of at least one of the tracks is executed, and a log entry is generated when a defect is detected. After the defect scan, a verify operation is executed for at least two of the detected defects. A number of times the verify operation detects a false defect is counted, and whether the head is defective is determined based at least partly on the count.
1. A data storage device comprising:
a disk comprising a plurality of tracks;
a head; and
control circuitry configured to:
defect scan at least one of the tracks and generate a log entry when a defect is detected;
after the defect scan, execute a verify operation for at least two of the detected defects;
count a number of times the verify operation detects a false defect; and
determine whether the head is defective based at least partly on the count.
2. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to generate the log entry when a target defect type is detected.
3. The data storage device as recited in claim 2 , wherein the count corresponds to a number of times the target defect type is falsely detected.
4. The data storage device as recited in claim 3 , wherein the target defect type comprises a drop-in defect.
5. The data storage device as recited in claim 3 , wherein the control circuitry is further configured to determine whether the head is defective based on a total number of log entries generated during the defect scan.
6. The data storage device as recited in claim 5 , wherein the control circuitry is further configured to determine the head is defective when the total number of log entries exceeds a threshold.
7. The data storage device as recited in claim 5 , wherein the control circuitry is further configured to determine the head is defective when the total number of log entries corresponding to a target defect type exceeds a threshold.
8. The data storage device as recited in claim 7 , wherein the target defect type comprises a drop-in defect.
9. A method of operating a data storage device, the method comprising:
defect scanning at least one track of a disk and generating a log entry when a defect is detected;
after the defect scan, executing a verify operation for at least two of the detected defects;
counting a number of times the verify operation detects a false defect; and
determining whether a head is defective based at least partly on the count.
10. The method as recited in claim 9 , further comprising generating the log entry when a target defect type is detected.
11. The method as recited in claim 10 , wherein the count corresponds to a number of times the target defect type is falsely detected.
12. The method as recited in claim 11 , wherein the target defect type comprises a drop-in defect.
13. The method as recited in claim 11 , further comprising determining whether the head is defective based on a total number of log entries generated during the defect scan.
14. The method as recited in claim 13 , further comprising determining the head is defective when the total number of log entries exceeds a threshold.
15. The method as recited in claim 13 , further comprising determining the head is defective when the total number of log entries corresponding to a target defect type exceeds a threshold.
16. The method as recited in claim 15 , wherein the target defect type comprises a drop-in defect.