Disk Write Omission Detection via Generation Number Comparison
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Solution Overview
Problem
Conventional methods fail to accurately detect disk write omissions, particularly when the entire area of a block remains unchanged, leading to undetected errors and potential data inconsistencies.
Innovation Solution
An apparatus and method that utilize an update state setting unit to generate and store a new update state value, comparing it with a confirmation value to detect discrepancies, ensuring accurate detection of disk write omissions even in the entire area of a block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional BCC check code method is used, then partial write omissions can be detected, but entire block write omissions cannot be detected
Solution Approach 1:
The patent segments the write verification process into two independent components: (1) traditional BCC check codes for partial error detection within blocks, and (2) a new generation number field that tracks update states across entire blocks. This segmentation allows each mechanism to specialize - BCC for intra-block errors and generation numbers for inter-block update tracking - thereby resolving the contradiction by enabling detection of both partial and entire block write omissions simultaneously
Solution Approach 2:
The patent introduces an intermediary mechanism - the generation number field stored in management data - that mediates between the write operation and the verification process. This intermediary tracks whether blocks have been updated by comparing generation numbers before and after writes, providing a reliable indicator of write omission at the block level that complements the BCC method's byte-level checking
2Reliability
If BCC check code is added to each block, then data error detection is improved, but detection of complete block write omissions fails
Solution Approach 1:
The patent merges two previously separate verification mechanisms into a unified system: the BCC check code method for detecting data errors within blocks, and the new generation number comparison method for detecting complete block write omissions. By combining these approaches in the management data structure, the system achieves both data error detection reliability and write omission detection precision simultaneously
3Measurement precision
If update state values are stored and compared, then write omission detection is improved, but system complexity increases
Solution Approach 1:
The patent changes the parameter being tracked from detailed data content verification to a simplified generation number indicator. Instead of complex verification of whether entire blocks were written, the system uses a simple integer generation number that increments with each update operation. This parameter transformation maintains high detection precision while significantly reducing the complexity of the verification mechanism
Data Source
AI summary
In the present invention, for each set of blocks [#(0) to #(N−1)] storing update data, a history block [#(N)] storing an update state value, for example, a generation, time or check code, showing an update state is provided, constituting a set of management data as a check object. When writing update data on a disk, a new update state value is calculated for the same set of management data and stored in memory as update state confirmation value. The new update state value is also set as write data in the history block in the same set of management data, and the entire of the set of management data including update data and update state value are written onto a disk. The history block is read and disk write omissions are detected by comparing the update state value and the update state confirmation value stored in memory.