Magnetic Disk Servo Data Caching to Reduce Read Errors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional magnetic disk apparatuses experience read errors in servo data, leading to retry processes that cause waiting times and deteriorate access performance due to frequent read errors of servo data recorded on the magnetic disk.
Innovation Solution
The magnetic disk apparatus stores second servo data in a NAND memory instead of the magnetic disk, allowing the system to acquire this data without accessing the disk, reducing read errors and improving access performance by using first and second servo data for positioning control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If servo data is stored on the magnetic disk and read by the magnetic head, then positioning control is achieved, but read errors occur frequently causing retry processes and waiting time
Solution Approach 1:
The patent creates a copy of the servo data storage function by implementing a servo data cache in the host system that mirrors the servo data normally stored on the magnetic disk. This cache copy allows the system to retrieve servo data without accessing the magnetic disk, thereby eliminating read errors and retry processes while maintaining positioning control functionality.
Solution Approach 2:
The servo data cache acts as an intermediary between the magnetic head positioning system and the magnetic disk storage medium. Instead of directly reading servo data from the disk, the system retrieves it from the cache intermediary, which provides reliable and rapid access without the errors associated with magnetic disk reading.
2Ease of operation
If servo data is read from the magnetic disk for positioning control, then magnetic head positioning is achieved, but access performance deteriorates due to frequent read errors
Solution Approach 1:
The system performs preliminary action by pre-loading and caching servo data in the host system's memory before it is needed for positioning operations. This advance preparation ensures that servo data is readily available when positioning is required, eliminating the need for time-consuming and error-prone disk access during critical positioning operations.
Solution Approach 2:
By creating a copy of servo data in the host system cache, the patent enables rapid retrieval for positioning control without repeatedly accessing the magnetic disk. This copy mechanism maintains positioning accuracy while dramatically improving access performance by eliminating disk read operations.
3Measurement precision
If the magnetic head accesses the magnetic disk to read servo data, then positioning control is performed, but the frequency of read errors increases
Solution Approach 1:
The patent eliminates read errors by copying servo data from the magnetic disk into a host system cache during initialization or idle periods. Subsequent positioning operations read from this error-free cache copy rather than accessing the magnetic disk directly, thereby maintaining measurement precision while achieving zero read errors.
Solution Approach 2:
The system applies beforehand cushioning by preparing and caching servo data in advance, creating a buffer against the unreliability of magnetic disk reading. This pre-prepared cache serves as a protective layer that shields the positioning system from read errors that would otherwise occur during normal operation.
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 configuration reduces the frequency of read errors and stabilizes the servo process, enhancing access performance by minimizing disk access for servo data, thus improving overall magnetic disk apparatus efficiency.
Implementation Method 1
a magnetic head configured to write data and read data to and from the magnetic disk
Data Source
AI summary
A magnetic disk apparatus according to an embodiment includes a magnetic disk, a magnetic head, a second memory, and a controller. On the magnetic disk, a servo sector where first servo data is recorded is provided. The magnetic head writes data and reads data to and from the magnetic disk. The first memory stores data to be written and stores data read from the magnetic disk. The second memory stores second servo data. The controller acquires the second servo data corresponding to the first servo data from the second memory based on the first servo data read by the magnetic head when passing over the servo sector. The controller executes positioning control of the magnetic head by using the first servo data and the second servo data.