Mapped RAID Restripe for Drive Utilization
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Solution Overview
Problem
Conventional data storage systems require adding multiple physical drives to create RAID groups, leading to unnecessary cost and complexity, especially when a single additional drive could suffice, and struggle with unlocking the capacity of a single drive in mapped-RAID environments due to lack of free storage space across other drives.
Innovation Solution
The techniques involve mapping out all drive extents in a data storage system to consume free space, determining excess free extents, and performing restriping to reduce orphaned storage, allowing data to be redistributed across drives, including considering relative wear and utilization for uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple physical drives are added to create RAID groups in conventional data storage systems, then storage capacity is increased, but system complexity and cost increase unnecessarily when a single drive would suffice
Solution Approach 1:
The patent segments the RAID group concept by allowing individual drives to be added independently rather than requiring complete RAID groups. Each drive can be dynamically integrated into the existing storage pool without requiring simultaneous addition of multiple drives, thus eliminating the need for complex RAID group management while maintaining storage capacity expansion.
Solution Approach 2:
The system dynamically adapts to variable drive configurations by allowing drives to be added or removed individually at any time. The storage management system automatically reconfigures data striping and distribution to accommodate changing drive counts, transforming the static RAID group structure into a dynamic storage pool that adjusts to actual hardware availability.
2Quantity of substance
If multiple physical drives are added to create RAID groups, then storage capacity is increased, but cost increases when a single additional drive would satisfy user needs
Solution Approach 1:
Instead of requiring complete RAID groups (excessive action), the system allows partial utilization of available drives. Users can add exactly the number of drives needed to meet storage requirements, and the system will utilize those drives proportionally, avoiding the waste of purchasing and deploying more drives than necessary.
3Quantity of substance
If a single additional drive is added to a mapped-RAID environment, then storage capacity is increased, but the capacity cannot be fully utilized due to insufficient free storage space on remaining drives
Solution Approach 1:
The system changes the fundamental parameter of data striping from fixed RAID group boundaries to dynamic drive-based allocation. By monitoring free space parameters across all drives and automatically redistributing data when free space thresholds are exceeded, the system ensures optimal utilization of available capacity regardless of whether drives are added in multiples or individually.
4Productivity
If data is restriped across drives to consume free storage space, then storage utilization is improved, but system operation time increases due to background restriping processes
Solution Approach 1:
The system implements periodic monitoring of drive free space thresholds and triggers restriping operations only when necessary. Rather than continuously monitoring and restriping, the system checks at intervals and activates background restriping processes only when free space exceeds predetermined thresholds, thus balancing storage optimization with minimal disruption to normal system operations.
Data Source
AI summary
Techniques for managing restriping of data across drives of a data storage system in a mapped-RAID environment. In response to addition of a drive to existing drives of the data storage system, all drive extents of the data storage system are mapped out in an effort to consume as much free space as possible across the drives. Having mapped out the drive extents, how many free extents remain on each drive is determined. If a quantity of free extents on a drive exceeds a predetermined threshold number, then that drive is logically marked as requiring restriping. Restriping of data is then performed for all logically marked drives. Once the restriping of the data is completed, a determination is made as to whether any further restriping of data across the drives of the data storage system is required, taking into account a relative wear and/or utilization of the respective physical drives.