RAID Data Extent Movement via Physical-Virtual Block Mapping
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Solution Overview
Problem
In RAID storage systems, the rebuild process after a drive failure is lengthy due to the need to recreate and redistribute data across healthy drives, which increases with the amount of data, and existing methods do not efficiently manage data movement and compaction, leading to prolonged processing times and wear on storage devices.
Innovation Solution
The method involves identifying and writing information about the relationship between physical layer blocks and virtual logic blocks within the RAID storage, including back pointers, to compact active data and update virtual logic blocks, allowing for targeted data movement and reduction of unnecessary data transfers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is evenly distributed across all drives in RAID storage, then data redundancy and fault tolerance are improved, but rebuild time after drive failure increases significantly
Solution Approach 1:
The patent introduces a two-layer mapping structure (virtual logic block to physical layer block, and physical layer block to stripe) that pre-organizes data relationships before failure occurs. This preliminary structuring enables faster identification and relocation of valid data during rebuild operations, reducing the time penalty associated with distributed data placement.
2Productivity
If all data blocks are moved during rebuild process, then data redistribution is completed, but processing time and device wear increase
Solution Approach 1:
The patent extracts and identifies only the valid data blocks that need to be relocated during rebuild operations, using the two-layer mapping to distinguish active data from obsolete blocks. By extracting only the necessary data movement operations rather than moving all blocks, the system completes redistribution while minimizing processing time and device wear.
3Loss of information
If back pointers are written within RAID storage stripes, then data relationship tracking is improved, but storage overhead increases
Solution Approach 1:
The patent makes the stripe structure serve multiple functions: it stores both user data and the back pointer metadata that tracks data relationships. By making the stripe multi-functional, the system achieves improved data relationship tracking without adding separate dedicated metadata storage structures, thus minimizing storage overhead while maintaining comprehensive tracking information.
Data Source
AI summary
A method, computer program product, and computer system for identifying, by a computing device, information associated with a relationship between a physical layer block and a virtual logic block for RAID storage. The information associated with the relationship between the physical layer block and the virtual logic block may be written within the RAID storage.