RAID-6 Controller Error Recovery Segmentation
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Solution Overview
Problem
RAID 6 data storage systems face inefficiencies in error recovery during read operations, as they require reading and decoding data from multiple storage devices, leading to prolonged recovery times due to uncorrectable errors.
Innovation Solution
A data storage device with a RAID 6 architecture that decodes a first data block and reads second data blocks from the same column to recover the first block upon read failure, reducing the amount of data transmitted and enhancing recovery efficiency by selecting the most appropriate recovery mode based on the number of failed blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RAID controller reads data from multiple storage devices to recover uncorrectable errors, then data reliability is improved, but error recovery time increases significantly
Solution Approach 1:
The patent segments the error recovery process into two distinct phases: (1) attempting ECC decoding first on the failed data block, and (2) only if that fails, then reading additional data blocks from the same column to perform recovery. This segmentation avoids the time-consuming multi-device read operation when it's not necessary, thus reducing average error recovery time while maintaining reliability.
Solution Approach 2:
The patent performs preliminary ECC decoding on the failed data block before attempting to read additional data blocks from storage devices. This preliminary action allows the system to correct many errors without invoking the slower recovery process, thereby reducing overall error recovery time while preserving data reliability.
2Reliability
If the RAID controller reads additional data blocks from storage devices for error recovery, then data recovery capability is improved, but data access speed deteriorates
Solution Approach 1:
The patent segments the recovery data source into two levels: first attempting to recover using only data blocks from the same column in the storage medium (faster access), and only if that fails, then accessing additional data blocks from storage devices (slower but more capable). This segmented approach optimizes the balance between recovery capability and access speed.
Solution Approach 2:
The patent applies local quality by prioritizing recovery methods that use locally available data (same column blocks already in or near the storage medium) before resorting to remote data blocks from other storage devices. This local-first strategy improves data access speed while maintaining adequate recovery capability for common error cases.
3Reliability
If the system performs ECC decoding on read data, then error correction capability is improved, but processing time increases
Solution Approach 1:
The patent performs ECC decoding as a preliminary and mandatory first step in the error recovery process, before considering any additional recovery methods. This preliminary decoding action corrects the majority of errors efficiently without requiring time-consuming additional data reads, thus reducing overall processing time while maintaining strong error correction capability.
Solution Approach 2:
The patent maintains continuous useful action by having the ECC decoder always active and attempting decoding on every read operation. This continuous decoding capability ensures that errors are corrected in real-time without interrupting the data access flow, thereby reducing perceived processing time while preserving error correction capability.
Data Source
AI summary
A data storage device is provided. The data storage device includes a storage medium configured to store data blocks included in a stripe set, and a controller connected to the storage medium and configured to, decode a first data block disposed in a column among the data blocks, during a read operation of the first data block, and read first group data blocks disposed in the column among the data blocks, based on a read failure of the first data block.