Storage Controller RAID Read Disturbance Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonvolatile memory devices, such as SSDs, experience read disturbances during repeated read operations, leading to increased read errors and reduced reliability due to the soft programming of memory cells, which is exacerbated by uneven distribution of read disturbances across memory blocks.
Innovation Solution
Implementing a method that uses RAID encoding and decoding to distribute and read data chunks and parity chunks across multiple memory blocks, allowing for direct or indirect read operations based on the storage device's operating state, thereby reducing the concentration of read disturbances and enhancing memory block reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If direct read operation is performed on target data chunk, then read speed is improved, but read disturbance concentration increases
Solution Approach 1:
The patent segments the read operation into two types: direct read operation for data chunks and indirect read operation for parity chunks. This segmentation allows the system to read data efficiently while distributing read disturbances across different memory blocks through the parity chunk mechanism, preventing concentration of read disturbances on a single memory block.
Solution Approach 2:
The parity chunk acts as an intermediary element in the RAID stripe. When a read operation is performed, the system reads both data chunks and parity chunks, using the parity information to reconstruct data if needed. This intermediary mechanism distributes read disturbances across multiple memory blocks, improving reliability without significantly impacting read speed.
2Reliability
If indirect read operation with RAID decoding is performed, then read disturbance distribution is improved, but read latency increases
Solution Approach 1:
The patent applies partial indirect read operations only when necessary (e.g., when data chunks are not directly accessible or when disturbance distribution is needed). For most read operations, direct read operations are used to minimize latency. The indirect read operation with RAID decoding is performed selectively to distribute read disturbances, balancing reliability improvement with latency minimization.
3Reliability
If RAID encoding is applied to data chunks, then data protection is improved, but storage complexity increases
Solution Approach 1:
The storage controller is designed to handle multiple read operation types (direct and indirect) and RAID operations (encoding and decoding) through a unified control mechanism. The controller uses a mapping structure that associates logical addresses with physical addresses and operation types, allowing it to manage RAID encoding/decoding and disturbance distribution without requiring separate complex subsystems for each function.
Data Source
AI summary
A method of operating a storage device including a plurality of nonvolatile memory devices and a storage controller, including: generating a parity chunk by performing a redundant array of independent disks (RAID) encoding on a plurality of data chunks; storing a data stripe including the plurality of data chunks and the parity chunk in a plurality of memory blocks included in the plurality of nonvolatile memory devices; and performing a direct read operation or an indirect read operation based on an operating state of the storage device such that in the direct read operation a target data chunk is directly read from the plurality of nonvolatile memory devices, and in the indirect read operation the target data chunk is generated by performing a RAID decoding.