Hard Disk LBA Mapping Without Reformatting
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Solution Overview
Problem
In hard disk devices, reformatting is required whenever logical block addresses (LBAs) are reassigned, leading to prolonged initialization times due to the need to rewrite cyclic redundancy check (CRC) data, resulting in CRC errors and unusable sectors if reformatting is not performed.
Innovation Solution
A method that omits reformatting by generating new LBA mappings and tracking differences between old and new generation LBAs, allowing sectors to be used without reformatting, by embedding generation information and LBA differences in CRC data, enabling correct LBA correction and sector usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reformatting is performed to rewrite CRC data based on new LBA, then CRC errors are prevented and sector usability is ensured, but initialization time is significantly prolonged
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the difference values between old and new LBA mappings in a difference information table before actual data access. This allows the system to quickly correct LBAs during operation without performing time-consuming reformatting operations, thus reducing initialization time while ensuring sector usability.
Solution Approach 2:
The patent extracts only the essential difference information between old and new LBA mappings from the complete reformatting process. Instead of rewriting all CRC data across the entire disk, the system extracts and stores only the necessary difference values in a compact table structure, enabling selective and efficient LBA correction without full reformatting.
2Productivity
If reformatting is omitted to reduce initialization time, then initialization time is reduced, but CRC errors occur and sectors become unusable
Solution Approach 1:
The patent introduces an intermediary mechanism - the difference information table - that mediates between the old and new LBA mappings. This table serves as a reference that allows the system to maintain sector usability without reformatting by providing the necessary correction information during data access operations.
Solution Approach 2:
The patent changes the parameter representation by storing LBA difference values instead of complete LBA mappings or performing full reformatting. This parameter transformation allows the system to achieve both fast initialization and reliable sector access by using compact difference information for LBA correction.
3Reliability
If complete reformatting is performed to ensure data integrity, then data integrity is maintained, but device complexity and processing overhead increase
Solution Approach 1:
The patent segments the reformatting process into two distinct parts: (1) pre-computation of LBA difference values stored in a difference information table, and (2) selective application of these differences during data access. This segmentation eliminates the need for complex full-disk reformatting operations while maintaining data integrity through targeted LBA correction.
Data Source
AI summary
A hard disk device accepts logical block addresses (LBAs) from a host. The hard disk device includes a disk having a plurality of physical sectors from which data is read and to which data is written, and a processor configured to perform read and write operations on the disk in response to read and write commands from the host that designate LBAs. The processor, in response to a request for initialization, does not perform any write operations on the disk, and generates a new mapping of LBAs to the physical sectors for a current generation based on unusable sectors detected during a previous generation, and tracks differences in correspondence between LBAs and the physical sectors between the current generation and the previous generation.