Mixed-Capacity RAID Expansion Without Node Replacement
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Solution Overview
Problem
Conventional RAID systems face difficulties in expanding storage capacity by incorporating higher-capacity storage devices into existing systems without requiring the replacement of all lower-capacity devices or adding storage nodes, limiting user options and increasing expansion costs.
Innovation Solution
The implementation of mixed-capacity storage devices, where higher-capacity storage devices are added to existing RAID systems to create extended and additional RAID groups, allowing for increased storage capacity without replacing lower-capacity devices or adding nodes, using parity information for data recovery and utilizing RAID 6 arrangements for fault tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional RAID systems use uniform storage capacity across all devices, then system reliability and data recovery are improved, but storage capacity expansion flexibility and cost-effectiveness deteriorate
Solution Approach 1:
The patent applies local quality by allowing different storage devices within the same RAID group to have different capacities. Specifically, the system supports a first set of storage devices with a first capacity and a second set with a second capacity, where the capacities can differ. This enables optimized capacity expansion while maintaining data recovery capabilities through extended RAID groups that accommodate heterogeneous device capacities.
2Quantity of substance
If all lower-capacity storage devices are replaced to expand capacity, then storage capacity increases, but system cost and complexity increase
Solution Approach 1:
The patent segments the storage system into multiple sets of storage devices with different capacities. The first set includes lower-capacity devices and the second set includes higher-capacity devices, allowing selective addition of higher-capacity devices without replacing the entire array. This segmentation enables incremental capacity expansion while preserving existing lower-capacity devices.
Solution Approach 2:
The patent merges different capacity classes into a unified RAID group structure. By creating extended RAID groups that combine the first set of lower-capacity devices and the second set of higher-capacity devices, the system achieves capacity expansion through consolidation rather than replacement, reducing overall system complexity.
3Quantity of substance
If storage nodes are added to expand capacity in distributed storage systems, then storage capacity increases, but system cost and infrastructure requirements increase
Solution Approach 1:
The patent implements universality by enabling existing storage nodes to perform multiple functions: they can host both the first set of lower-capacity devices and the second set of higher-capacity devices within the same node. This multi-functional approach allows capacity expansion without requiring separate dedicated nodes for different capacity tiers, reducing infrastructure requirements.
Data Source
AI summary
A storage system comprises a plurality of storage devices, with the storage devices comprising a first set of storage devices each having a first capacity and a second set of storage devices each having a second capacity higher than the first capacity. The storage system is further configured to establish an extended redundant array of independent disks (RAID) group to extend existing RAID stripes of the storage devices of the first set into the storage devices of the second set, and to establish an additional RAID group for the storage devices of the second set, the additional RAID group comprising one or more additional RAID stripes for the storage devices of the second set. The storage devices of the second set are illustratively added to the storage system to expand its capacity beyond that provided by the storage devices of the first set. Other embodiments include methods and computer program products.