Dirty Time Log Resilvering for Storage Pool Data Integrity
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Solution Overview
Problem
Existing data backup schemes, such as mirroring, face inefficiencies in resynchronization processes due to system overhead and time consumption, especially when dealing with large regions or small modifications in file storage devices.
Innovation Solution
A method and system that utilize a dirty time log (DTL) to identify specific blocks requiring resilvering in a storage pool, where a block's birth time is checked against the DTL to determine if resilvering is necessary, allowing for targeted resynchronization rather than full device resynchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full device resynchronization is performed, then data integrity is ensured, but time consumption and system overhead increase significantly
Solution Approach 1:
The patent segments the resynchronization process by dividing the storage device into regions and tracking dirty regions individually. Instead of synchronizing the entire device, only the dirty regions are resynchronized, reducing the time consumption while maintaining data integrity through targeted synchronization operations.
Solution Approach 2:
The patent applies partial action by resynchronizing only the necessary dirty regions rather than the entire device. The dirty time log mechanism allows the system to identify and synchronize only the specific regions that require attention, avoiding the excessive action of full device resynchronization.
2Productivity
If dirty region logging is used to track modifications, then resynchronization efficiency improves, but system overhead increases due to DRL updates
Solution Approach 1:
The patent implements preliminary action by creating a dirty time log that records modification information in advance. This log structure is established before resynchronization occurs, allowing the system to efficiently identify dirty regions without performing complex operations during the resynchronization process itself.
Solution Approach 2:
The patent uses a simplified copying approach where instead of tracking every individual modification detail, the system copies only the essential dirty region information into the dirty time log. This selective copying reduces the overhead of maintaining the log while preserving the ability to identify regions needing resynchronization.
3Measurement precision
If region size is made small for precise tracking, then modification accuracy improves, but overhead for resynchronizing regions increases
Solution Approach 1:
The patent applies local quality by allowing different regions to have different synchronization characteristics. Small regions maintain precise modification tracking for critical data, while larger regions can be handled with simpler synchronization operations. The dirty time log enables the system to apply appropriate quality levels to each region based on its specific needs.
Data Source
AI summary
A method for resilvering a storage pool includes identifying a live block in the storage pool, determining whether a birth time associated with the live block is on a dirty time log (DTL), and resilvering the live block, if the birth time is on the DTL.