Magnetic Disk Off-Track Error Handling via Nonvolatile Memory Buffer
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Solution Overview
Problem
The shingled write recording method on magnetic disks often results in off-track errors due to vibrations, leading to data being written outside intended tracks, causing interference with neighboring tracks and making it difficult to read or rewrite data, which disrupts continuous writing and reading processes.
Innovation Solution
A magnetic disk apparatus with a determination module to detect off-track errors, a write module to temporarily store data in nonvolatile memory until the error is corrected, and a read module to manage data retrieval using ITI cancellation techniques, ensuring continuous data processing and maintaining recording density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If shingled write recording method is used to increase recording density, then data writing density is improved, but off-track errors occur more frequently due to vibrations
Solution Approach 1:
The patent applies preliminary action by detecting off-track errors before they cause data loss. The determination module continuously monitors track positioning during the shingled write process, and when an off-track error is detected, the system proactively switches to nonvolatile memory storage for affected data, preventing the error from propagating and ensuring data integrity while maintaining high recording density
2Reliability
If write processing is interrupted to correct off-track errors, then tracking accuracy is improved, but productivity decreases due to continuous interruption
Solution Approach 1:
The patent introduces nonvolatile memory as an intermediary buffer between the magnetic disk and the data processing system. When off-track errors are detected, data are temporarily stored in this intermediary nonvolatile memory, allowing the write processing on the magnetic disk to be interrupted and corrected without permanently stopping the overall data flow. This mediator enables error correction while maintaining continuous data processing capability
Solution Approach 2:
The system performs preliminary detection of off-track errors using the determination module before they significantly impact productivity. By detecting errors early and switching to nonvolatile memory storage proactively, the system minimizes the duration of interruptions and maintains higher overall writing speed compared to systems that detect and respond to errors only after they have already caused data corruption
3Reliability
If data are rewritten to correct off-track errors, then data integrity is improved, but magnetic interference with neighboring tracks increases
Solution Approach 1:
The patent extracts problematic data that have suffered off-track errors from the magnetic disk medium and relocates them to nonvolatile memory. By taking out these corrupted data segments and storing them in a different medium (nonvolatile memory instead of magnetic disk), the system corrects data integrity issues while eliminating the need for repeated magnetic writing operations that would generate additional magnetic interference with neighboring tracks
Solution Approach 2:
Nonvolatile memory serves as an intermediary storage medium that allows data to be rescued from off-track errors without requiring immediate rewriting back to the magnetic disk. This intermediary storage enables data integrity restoration while breaking the cycle of repeated magnetic write operations that cause inter-track interference, as data can be staged in nonvolatile memory and only rewritten to disk when tracking conditions are optimal
Data Source
AI summary
According to at least one embodiment, a magnetic disk apparatus includes a magnetic disk, a nonvolatile memory, a determination module, a write module, and a read module. The determination module determines whether the off-track write occurs on a first data sector during a write mode. The write module writes first data in the nonvolatile memory if the determination module determines that the off-track write occurs on the first data sector. The read module reads the first data from one of the magnetic disk and the nonvolatile memory based on a determination result of the determination module.