RAID Media Error Recovery via PRRQ Batch Rebuild
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Solution Overview
Problem
RAID systems face challenges in efficiently recovering from media errors, particularly when a cluster of errors occurs, leading to increased recovery time and potential performance degradation.
Innovation Solution
The implementation of a parity RAID request format (PRRQ) frame allows for the identification and recovery of multiple data storage units with errors using a single request, reducing the number of rebuild requests and minimizing recovery time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional individual rebuild requests are issued for each bad block, then each error can be recovered, but the recovery time increases significantly when multiple errors occur
Solution Approach 1:
The patent combines multiple individual rebuild requests into a single batched rebuild request. The RAID controller identifies multiple bad blocks and issues one consolidated rebuild request containing all affected block addresses, allowing parallel recovery of multiple blocks simultaneously rather than sequentially processing each block individually.
Solution Approach 2:
The patent segments the error recovery process into two phases: error identification phase where bad blocks are detected and collected, and batched execution phase where multiple rebuild operations are consolidated into a single request. This segmentation allows efficient grouping of recovery operations.
2Reliability
If multiple individual rebuild requests are issued for multiple bad blocks, then all errors can be recovered, but the number of requests increases system overhead and reduces efficiency
Solution Approach 1:
The patent merges multiple separate rebuild requests into a single batched request structure. Instead of issuing N individual requests for N bad blocks, the system creates one consolidated request that contains an array of all bad block addresses, reducing the number of request-response cycles and associated protocol overhead.
3Reliability
If sequential rebuild operations are performed for each bad block, then recovery is thorough, but system performance degrades during recovery
Solution Approach 1:
The patent combines multiple sequential rebuild operations into a single batched operation that executes in parallel. The RAID controller processes all bad blocks in the batch simultaneously rather than one at a time, maintaining data integrity while significantly improving system performance during the recovery process.
Data Source
AI summary
In some aspects, a method may include identifying, by one or more processors, a presence of an error in a plurality of data storage units in a range of data storage units of an error bitmap of a redundant array of independent disks (RAID). The method may include generating, by the one or more processors, a parity RAID request format (PRRQ) frame, the PRRQ frame identifying the range of data storage units, where at least one data storage unit has an error, the range of data storage units identified at least in the plurality of data storage units. The method may include communicating, by the one or more processors, the PRRQ frame to a controller, the controller is configured, responsive to the PRRQ frame, to recover the data in the range of data storage units in the plurality of data storage units.