Disk Controller Error Detection for Unallocated Pool Volume Initialization
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Solution Overview
Problem
In RAID systems, rebuilding processes can lead to the creation of uncertain data in unallocated areas of storage pools, causing data loss and rendering affected areas unusable, especially when errors occur during data reconstruction.
Innovation Solution
A disk controller with a processor that detects errors in pool volumes, determines if the affected pool volume is allocated to a logical volume, and initializes the unallocated pool volume to prevent data corruption and ensure data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rebuilding process is performed in the storage pool, then data redundancy is restored, but BAD data may be created in unallocated real areas causing data loss
Solution Approach 1:
The patent applies preliminary action by performing formatting processing on unallocated real areas before the rebuilding process completes. The disk controller detects unallocated areas during rebuilding and proactively formats them to prevent BAD data creation, rather than waiting for errors to occur. This advance preparation eliminates the harmful effect before it can manifest.
Solution Approach 2:
The patent converts the potential harm of BAD data creation into a benefit by using the rebuilding process itself to identify and format unallocated areas. The error detection mechanism during rebuilding is transformed into a proactive formatting trigger, turning a potentially harmful situation into an opportunity to prevent future data corruption.
2Loss of information
If BAD data is written to indicate failed blocks, then data loss is explicitly marked, but unallocated areas may contain uncertain data that is not properly initialized
Solution Approach 1:
The patent applies local quality by treating allocated and unallocated areas differently. For allocated areas, BAD data is written to indicate failures. For unallocated areas, formatting processing is performed to initialize the data. This localized differentiation ensures that each type of area receives the appropriate treatment for its specific state and usage requirements.
Solution Approach 2:
The patent performs formatting processing as a preliminary action on unallocated areas before they are subsequently allocated or used. By initializing these areas during the rebuilding process, the system ensures that when allocation occurs later, the data is already in a known good state, preventing uncertain data from being used.
3Adaptability or versatility
If the storage pool allows dynamic allocation, then resource utilization is improved, but the risk of creating uncertain data in unallocated areas increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the allocation state of real areas during the rebuilding process. The disk controller detects which areas are unallocated and uses this information to trigger formatting processing. This feedback mechanism ensures that dynamic allocation flexibility is maintained while simultaneously preventing uncertain data creation in unallocated areas.
Solution Approach 2:
The system performs self-service by automatically detecting unallocated areas and initiating formatting processing without requiring external intervention. The disk controller autonomously manages the formatting of unallocated areas during rebuilding, eliminating the need for explicit formatting instructions from the host computer and ensuring data integrity is maintained throughout the dynamic allocation process.
Data Source
AI summary
A disk controller for controlling disk devices for storing redundant data distributed thereacross, the disk devices providing a logical volume, the disk devices including pool volumes allocatable to one of the logical volume. The disk controller includes a memory for storing information indicating a relationship between the pool volumes and the logical volume; and a processor for performing data reconstruction in accordance with a failure of the disk devices, a process of the data reconstruction, the processor being configured to detect an error in a part of the pool volumes included in the other disk devices when reading data from the pool volumes included in the other disk devices, determine whether the detected pool volume is allocated to the logical volume in reference to the information, and initialize the part of the detected pool volume when the detected pool volume is unallocated to the logical volume.