Magnetic Disk RW Channel Selective Data Rewriting
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Solution Overview
Problem
Current hard disk drives (HDDs) face inefficiencies in data processing due to the need to transfer and process entire data units, even when only a portion needs to be rewritten, leading to increased time and potential errors in error correction processing.
Innovation Solution
A magnetic disk apparatus with a read/write channel module and processor that allows for selective rewriting of only the necessary data portion by using internal memory for error correction and buffering, reducing the need to transfer and process entire data units, and optimizing data paths to minimize errors and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the data size unit based on magnetic disk format is increased to improve medium usage efficiency, then the efficiency of use of the medium increases, but more time is required to process small amounts of data
Solution Approach 1:
The patent divides the data processing into two independent paths: a first path for small data amounts that bypasses the data buffer, and a second path for large data amounts that uses the data buffer. This segmentation allows small data to be processed quickly without waiting for buffer operations, while large data still benefits from buffer-based processing, thus resolving the contradiction between medium efficiency and processing speed.
Solution Approach 2:
The patent implements partial action by determining whether to use the data buffer based on the data amount. For small data amounts, the system performs only the necessary error correction processing without the excessive action of reading and writing entire data units to the buffer, thereby reducing processing time while maintaining medium efficiency for larger operations.
2Reliability
If error correction processing is performed on the entire data unit when only a portion needs to be rewritten, then data protection is maintained, but the time required for processing increases
Solution Approach 1:
The patent segments the error correction processing into two scenarios: for small data amounts, error correction is performed only on the specific data portion without buffer involvement; for large data amounts, error correction is performed on the entire data unit through the buffer. This segmentation maintains data protection reliability while minimizing processing time for small operations.
Solution Approach 2:
The system applies different processing qualities to different data amounts: small data receives localized error correction processing that is faster and more efficient, while large data receives comprehensive buffer-based error correction. This local quality approach ensures data protection is maintained appropriately for each case without unnecessary processing overhead.
3Speed
If the first path for small data amounts is implemented, then processing speed improves, but the complexity of the data transfer control increases
Solution Approach 1:
The patent implements dynamic control by using a determination unit that dynamically selects the processing path based on the data amount. The transfer controller dynamically switches between the first path (direct processing) and second path (buffer-based processing), allowing the system to adapt to different data sizes and maintain optimal speed while managing complexity through conditional logic rather than fixed architecture.
Data Source
AI summary
According to one embodiment, a magnetic disk apparatus includes an RW channel with an internal memory for processing data to be read/written from/to a magnetic disk, a transfer controller for controlling data transfer between a host apparatus and the RW channel, and a processor for controlling the RW channel and transfer controller. The processor reads, from the magnetic disk, predetermined area data including to-be-rewritten data, subjects the read predetermined area data to error correction processing in the RW channel, and stores resultant data in the internal memory. The processor rewrites, with rewrite data from the host apparatus, the to-be-rewritten data of the predetermined area data stored in the internal memory to update the predetermined area data, adds an error correction code to the updated data in the RW channel module, and writes resultant data to the magnetic disk.