RAID Drive Array Expansion via Sequential Cell Relocation
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Solution Overview
Problem
The relocation of RAID protection group members in data storage systems incurs significant overhead costs due to the need for computational and memory resources, which can be avoided by minimizing data movement during the expansion of storage capacity by adding new drives.
Innovation Solution
A method and apparatus that configure a primary drive array with sequentially ordered cells, assign sequential indices to new drives, and relocate protection group members to create free space across selected cell indices on new drives, thereby reducing data movement and optimizing storage capacity expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If new drives are added to expand storage capacity, then storage capacity is increased, but data movement overhead increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the primary drive array with sequentially ordered cells and establishing a specific distribution pattern for protection group members before expansion occurs. When new drives are added, the system can immediately utilize the pre-established sequential structure to minimize data movement, as the relocation pattern is already determined by the initial configuration.
Solution Approach 2:
The patent segments the drive array into sequentially ordered cells with specific distribution patterns, where protection group members are distributed across drives in a predetermined sequence. This segmentation allows for efficient identification and relocation of specific cells during expansion, reducing the computational overhead by avoiding full array reconfiguration.
2Adaptability or versatility
If protection group members are relocated during drive expansion, then new protection groups can be created, but computational resources are consumed
Solution Approach 1:
The patent changes the parameter of cell distribution by using sequential ordering and wrapping patterns. When expansion occurs, the system modifies only the necessary parameters (adding new drives and their sequential indices) while maintaining the existing sequential distribution pattern, thereby reducing reconfiguration complexity while enabling new protection group creation.
3Loss of energy
If sequential cell distribution is used, then data movement is minimized, but initial configuration complexity increases
Solution Approach 1:
The patent implements self-service through automatic sequential indexing and wrapping distribution. The system automatically assigns sequential indices to drives and distributes protection group members across cells in a predetermined pattern without requiring manual intervention, thereby reducing initial configuration complexity while achieving minimal data movement during expansion.
Data Source
AI summary
New drives numbering fewer than a RAID width W are added to a primary drive array of K=W+1 sequentially-ordered original drives with same-size sequentially-ordered cells, where RAID groups are sequentially ordered and distributed such that a first cell of each sequentially-ordered drive contains a RAID group member in the sequential order of the protection groups and subsequent cells of each original drive in sequence contain members in the sequential order, wrapped. The new drives are added by selecting a subset of the original drives adjacent to the new drives such that the selected new drives and original drives total W, selecting a number of sequential cell indices equal to the number of new drives, and relocating protection group members in the selected sequential cell indices on the selected original drives to the new drives such that free space is created across W cells of each of the selected cell indices.