Flexible RAID SSD Controller Page Grouping
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Solution Overview
Problem
Traditional RAID schemes in SSDs are inflexible and fail if any element in the RAID group becomes corrupted, leading to data loss and reduced reliability, despite the use of advanced error correction algorithms.
Innovation Solution
A flexible RAID system for SSDs that organizes flash memory pages into RAID line groups, excludes corrupted pages from parity calculations and reconstruction, and uses XOR processes to recover data, with RAID line group membership information stored in each page to identify excluded pages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RAID schemes are used in SSDs, then data redundancy is provided, but the system fails if any element in the RAID group becomes corrupted
Solution Approach 1:
The patent implements dynamic RAID group management where the composition of RAID groups can change over time. When pages are corrupted, the system dynamically reconfigures RAID groups to exclude bad pages and form new groups with remaining good pages, allowing the system to adapt to degradation rather than failing statically.
Solution Approach 2:
The system changes the parameter of RAID group membership by maintaining multiple generations of RAID groups. Old RAID groups are preserved in history while new groups are formed from remaining good pages, allowing the system to transition between different states of data redundancy and adaptability.
2Reliability
If all elements in a RAID group must be good, then data integrity is maintained, but storage capacity is reduced when pages become corrupted
Solution Approach 1:
The patent discards corrupted pages from active RAID groups but recovers storage capacity by forming new RAID groups from remaining good pages. The system recycles previously bad pages once they are repaired or when new pages become available, maximizing the utilization of storage capacity while maintaining data integrity through continuous reconfiguration.
Solution Approach 2:
The system dynamically adjusts the composition of RAID groups to maximize usable capacity. As pages are corrupted and repaired over time, the RAID group membership changes to include the maximum number of good pages, thereby recovering storage capacity that would otherwise be lost in static RAID configurations.
3Reliability
If multiple RAID groups are maintained with history, then flexibility and reliability are improved, but device complexity increases
Solution Approach 1:
The patent segments RAID group management into distinct components: active RAID groups for current data operations and historical RAID groups for record-keeping. This segmentation allows the system to maintain multiple generations of RAID groups without creating a monolithic complex structure, as each segment can be managed independently with specific purposes.
Solution Approach 2:
The system extracts and separates the management of old RAID groups from active RAID operations. Historical RAID groups are taken out into a separate history structure, allowing them to be preserved for reliability purposes without interfering with the performance and simplicity of active RAID group management.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the reliability of SSDs by tolerating single or multiple page failures, extending the drive's life and maintaining data integrity through flexible grouping and error correction.
Implementation Method 1
uses XOR processes to recover data
Data Source
AI summary
A solid state drive (SSD) employing a redundant array of independent disks (RAID) scheme includes a flash memory chip, erasable blocks in the flash memory chip, and a flash controller. The erasable blocks are configured to store flash memory pages. The flash controller is operably coupled to the flash memory chip. The flash controller is also configured to organize certain of the flash memory pages into a RAID line group and to write RAID line group membership information to each of the flash memory pages in the RAID line group.