Memory Controller Read Reclaim for SSD Data Integrity
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Solution Overview
Problem
Storage devices face issues with data damage due to frequent read operations, known as 'read disturb,' which can lead to increased boot times and data recovery challenges, especially when system data is repeatedly loaded and copied between blocks.
Innovation Solution
A storage device with a memory controller that performs a read reclaim operation by copying system data from a source block to a destination block based on the distance between erased and loaded pages, using information obtained during the system block loading operation, to mitigate data damage and prevent increased boot times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If system data is frequently read during boot operations, then the system can be initialized, but read disturb occurs causing data damage and increased boot times
Solution Approach 1:
The patent performs read reclaim operations during idle periods before boot operations are needed. System data is proactively copied from source blocks to destination blocks during low-activity periods, so that when boot operations occur, the data is already in a safe location and can be read without causing read disturb damage. This preliminary action prevents the contradiction by preparing the data beforehand.
Solution Approach 2:
The patent introduces destination blocks as intermediary storage locations. Instead of repeatedly reading from source blocks during boot, the system uses destination blocks as intermediaries that hold copies of system data. This intermediary structure allows boot operations to read from the destination block without causing read disturb to the original source block, thus maintaining data integrity while enabling fast boot.
2Reliability
If read reclaim operations are performed frequently to prevent read disturb, then data integrity is maintained, but system complexity and operation overhead increase
Solution Approach 1:
The patent applies read reclaim operations selectively rather than uniformly to all system data. The controller identifies specific source blocks that have undergone read disturb and targets only those for copy operations. This local quality approach focuses resources on problematic areas while leaving other data untouched, reducing overall system complexity and operation overhead compared to universal read reclaim.
Solution Approach 2:
The patent monitors parameters such as read count thresholds and block status to determine when read reclaim operations are necessary. By changing operational parameters based on actual data conditions rather than performing fixed-schedule operations, the system reduces unnecessary complexity while maintaining data integrity. The controller adjusts its behavior based on detected parameters like the number of read operations performed on source blocks.
Data Source
AI summary
Provided herein may be a storage device and a method of operating the storage device. The storage device includes a memory device including a plurality of system blocks; and a memory controller configured to perform a read reclaim operation of copying system data stored in a selected system block to another one of the plurality of system blocks using information obtained during loading of the system data into the selected system block.