HDD Verify First Write Defect Detection
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Solution Overview
Problem
The high cost and time-consuming nature of defect-identifying disk surface scans in hard disk drive manufacturing pose a significant challenge in reducing manufacturing costs.
Innovation Solution
Implementing a 'verify first write' procedure where a read-verify operation is performed only for the first write to each storage area, marking defective areas and avoiding subsequent full disk surface scans, thereby allowing normal writing to verified areas without re-verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete disk surface scans are performed to identify all defects, then data integrity and reliability are improved, but manufacturing time and cost increase significantly
Solution Approach 1:
The patent applies preliminary action by performing a read-verify operation immediately after the first write operation to each storage area, before any subsequent writes occur. This preliminary verification identifies defects early, allowing the system to mark defective areas and avoid them in future operations, thereby maintaining data integrity without requiring complete disk surface scans throughout the entire manufacturing process
Solution Approach 2:
The patent applies partial action by performing verification only for the first write to each storage area rather than scanning the entire disk surface repeatedly. This selective verification approach checks sufficient areas to identify defects while significantly reducing the total time and resources required compared to comprehensive continuous scanning
2Reliability
If complete disk surface scans are performed to identify all defects, then data integrity and reliability are improved, but manufacturing cost increases
Solution Approach 1:
The patent applies preliminary action by performing a read-verify operation immediately after the first write operation to each storage area, before any subsequent writes occur. This preliminary verification identifies defects early, allowing the system to mark defective areas and avoid them in future operations, thereby maintaining data integrity without requiring complete disk surface scans throughout the entire manufacturing process
Solution Approach 2:
The patent applies partial action by performing verification only for the first write to each storage area rather than scanning the entire disk surface repeatedly. This selective verification approach checks sufficient areas to identify defects while significantly reducing the total time and resources required compared to comprehensive continuous scanning
3Reliability
If read-verify operations are performed for every write operation, then data integrity is ensured, but writing speed and productivity decrease
Solution Approach 1:
The patent applies preliminary action by performing a read-verify operation immediately after the first write operation to each storage area, before any subsequent writes occur. This preliminary verification identifies defects early, allowing the system to mark defective areas and avoid them in future operations, thereby maintaining data integrity without requiring complete disk surface scans throughout the entire manufacturing process
Solution Approach 2:
The patent applies feedback by using the results of the initial read-verify operation to determine whether subsequent write operations need verification. Once a storage area is verified as good, the system feeds back this information and allows normal writing without re-verification, while defective areas are marked and avoided, thus maintaining both integrity and speed
4Loss of time
If defective areas are marked and avoided, then manufacturing time is reduced, but the complexity of tracking and managing verified areas increases
Solution Approach 1:
The patent applies self-service by having the storage system automatically track and manage verified areas through its own operational processes. The read-verify operation and subsequent marking of defective areas are performed automatically by the system's built-in control mechanisms, eliminating the need for external tracking systems or complex manual management processes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes manufacturing time and costs by eliminating the need for comprehensive defect-identifying disk surface scans during HDD production, while ensuring data integrity through initial verification and subsequent efficient data storage.
Implementation Method 1
A write head works by using the current flowing through its coil to produce a magnetic field. Electrical pulses are sent to the write head, with different patterns of positive and negative currents. The current in the coil of the write head produces a localized magnetic field across the gap between the head and the magnetic disk, which in turn magnetizes a small area on the recording medium.
Implementation Method 2
A read-write head makes use of magnetic fields to write data to, and read data from, the surface of a magnetic-recording disk.
Data Source
AI summary
Identifying recording disk defects in a data storage device such as a hard disk drive (HDD), for which disk defects are not previously identified, includes responsive to a first user data write request to a particular storage area of a disk medium, writing the user data to the particular storage area, reading the written user data from the particular storage area, and verifying the integrity of the user data read from the particular storage area. Upon passing, a second user data write request to the same particular storage area can be fulfilled without again reading and verifying. Upon failing, the particular storage area is marked as defective and the user data is written to a different storage area. This procedure can be repeated in response to each initial user write request to each storage area of each disk medium, foregoing the need for disk surface scanning during manufacturing.