Volatile Memory Read Cache Reassignment for Error-Prone Areas
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Solution Overview
Problem
In storage systems with volatile memory, errors in reading data lead to increased unavailable storage areas due to indiscriminate handling of temporary and permanent errors, which are not differentiated.
Innovation Solution
A control device sets storage areas with errors as read cache areas for read data, differentiating between temporary and permanent errors and managing them accordingly, using error counters to determine when to replace or rewrite data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If storage areas with errors are immediately set as unavailable, then data integrity is maintained, but the number of unavailable storage areas increases
Solution Approach 1:
The patent segments storage areas into different types (read cache areas, write cache areas, ordinary areas) based on their error characteristics and usage patterns. By segmenting the error handling approach, the system can apply different strategies to different storage areas, allowing error-prone areas to be reused as read cache areas while maintaining data integrity through appropriate access controls and error correction mechanisms.
Solution Approach 2:
The patent changes the operational parameters of storage areas experiencing errors by transitioning them from ordinary storage areas to read cache areas. This parameter change allows the storage area to continue being used with modified access characteristics - specifically, data is rewritten periodically and read operations are controlled, thereby maintaining reliability while preserving storage capacity.
2Reliability
If error correction measures are applied to all storage areas, then data reliability is improved, but system complexity increases
Solution Approach 1:
The patent applies local quality by implementing error correction and data management measures specifically in read cache areas rather than uniformly across all storage areas. The system identifies storage areas with high error rates and applies specialized handling (periodic rewriting, controlled read access) only to those specific areas, thereby improving data reliability where needed without adding complexity to the entire system.
Solution Approach 2:
The patent introduces an intermediary management layer that mediates between storage areas and the host system. This intermediary (the storage device controller) implements error correction codes, manages the transition of storage areas between different types, and controls data access patterns. By concentrating the complexity in this intermediary layer rather than distributing it throughout the system, the patent achieves improved reliability while managing system complexity effectively.
3Reliability
If storage areas are frequently replaced when errors occur, then data integrity is maintained, but productivity decreases
Solution Approach 1:
The patent applies preliminary action by proactively rewriting data in read cache areas at scheduled intervals before errors can compromise data integrity. Instead of reacting to errors by replacing storage areas, the system preemptively refreshes data in error-prone areas, thereby maintaining reliability while avoiding the productivity loss associated with frequent area replacement and data migration.
Solution Approach 2:
The patent converts the harmful effect of high error rates in certain storage areas into a beneficial situation by designating these areas as read cache areas with controlled access patterns. The periodic rewriting mechanism transforms what would be a reliability problem into an opportunity for optimized storage utilization, as these areas continue to function effectively for read operations while maintaining data integrity through controlled rewriting rather than replacement.
Data Source
AI summary
A control device is configured to control a volatile memory. The control device is configured such that when an error has occurred in reading data stored in a storage area of the volatile memory and an error occurrence situation in the storage area in which the error has occurred satisfies a predetermined first occurrence condition, the control device sets the storage area in which the error has occurred as a read cache area which is used to store read data read from a predetermined storage medium.