Parity Distributed RAID Spare Space Layout Mapping
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Solution Overview
Problem
Existing parity declustered RAID (PDRAID) configurations are unable to efficiently distribute spare space in a nearly random permutation configuration, leading to performance bottlenecks during data recovery and reconstruction.
Innovation Solution
A method and apparatus for defining a layout mapping function in a parity distributed RAID array, which involves specifying target objects, allocating spare space, and adding columns to form a complete matrix, allowing for pseudo-random permutation and efficient distribution of spare space to aid in data reconstruction and recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional parity declustered RAID configurations are used, then data redundancy and fault tolerance are provided, but spare space cannot be efficiently distributed leading to performance bottlenecks during data recovery
Solution Approach 1:
The patent segments the RAID array into distinct functional zones: a first region containing data and parity stripes, and a second region containing spare stripes. This spatial segmentation allows independent optimization of each region - the first region maintains conventional RAID operations while the second region is专门 designed for efficient data reconstruction during failures, eliminating the performance bottleneck of uniformly distributed spare space.
Solution Approach 2:
The patent introduces a dimensional separation by organizing spare space not scattered across all drives (2D distribution) but concentrated in a dedicated second region (1D dedicated zone). This dimensional change allows the system to access spare space more efficiently during recovery operations, as the second region can be independently accessed without interfering with normal data operations in the first region.
2Productivity
If spare space is distributed across all drives, then recovery workload is balanced, but individual drives become overloaded during reconstruction operations
Solution Approach 1:
The patent divides the RAID array into a first region for active data/parity operations and a second region for dedicated spare space. During recovery operations, the system segments the reconstruction process into reading from the first region and writing to the second region, which simplifies load management compared to redistributing across all drives.
Solution Approach 2:
The second region acts as an intermediary buffer during data recovery. Instead of directly reconstructing data across all drives (which creates complex load balancing requirements), the system uses the second region as a temporary destination for reconstructed data, simplifying the recovery process and reducing individual drive overload.
3Productivity
If conventional RAID layouts are used, then data can be stored efficiently, but recovery operations become slower due to inefficient spare space utilization
Solution Approach 1:
The patent performs preliminary action by pre-allocating and pre-positioning spare space in the second region before any failure occurs. This ensures that when a failure happens, the spare space is immediately available and optimally positioned for rapid data reconstruction, eliminating the time loss associated with locating and accessing scattered spare space across conventional RAID layouts.
Data Source
AI summary
Method of defining a layout mapping function for a parity distributed RAID array including target objects, the layout mapping function defining the mapping of the stripe group-address space to the target-address space in the array and including a matrix defining a unit space across target objects, the matrix includes columns defining the objects and rows defining equally-offset sequential units on the objects, the method including: specifying P target objects, where P>1; b) specifying A target objects as spare space, where A<P and A≧1; defining a sub-matrix of P′ columns, where P′=P−A; defining a layout of stripe groups across the P′ target objects in the sub-matrix, each stripe group comprising data units and parity units; adding A columns, representative of the A spare space target objects, to the sub-matrix to form a complete matrix defining the layout mapping function; and implementing the layout mapping function on the objects.