Non-Volatile Memory Controller for Aging Block Data Migration
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Solution Overview
Problem
Non-volatile memory data retention reliability decreases over time, leading to unreliable stored data.
Innovation Solution
A non-volatile memory controller that records time stamps for each block, performs reliability checks based on critical time limits, and migrates data to spare spaces when blocks fail to meet reliability standards, using error correction codes and adaptive critical time limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored in non-volatile memory blocks over time, then storage capacity is utilized, but data retention reliability decreases
Solution Approach 1:
The system performs preliminary reliability checks on blocks before their data becomes unreliable. Time stamps are recorded when blocks are programmed, and the controller proactively identifies blocks approaching their reliability threshold and migrates their data to spare blocks before actual data loss occurs, rather than waiting for failure to happen.
Solution Approach 2:
The system implements a feedback mechanism where the controller continuously monitors block ages against critical time limits, evaluates reliability status, and triggers data migration when thresholds are exceeded. This closed-loop control ensures data is moved from at-risk blocks to spare blocks based on real-time reliability assessment.
2Reliability
If reliability checks are performed on all blocks, then data integrity is maintained, but processing time and complexity increase
Solution Approach 1:
Instead of uniformly checking all blocks, the system applies reliability checks selectively based on local conditions - specifically, only blocks whose age exceeds their critical time limit are subjected to reliability evaluation and potential migration. This localized approach focuses resources on at-risk blocks while leaving healthy blocks undisturbed.
Solution Approach 2:
The system uses time stamps and critical time limits as dynamic parameters to determine which blocks require attention. By comparing the age parameter (current time minus time stamp) against the critical threshold, the system automatically identifies blocks needing reliability checks, making the checking process adaptive rather than static.
3Reliability
If data is migrated frequently to maintain reliability, then data retention is improved, but write operations and wear increase
Solution Approach 1:
Data migration is performed preliminarily - before blocks actually fail - by monitoring block age and triggering migration when critical time limits are approached. This proactive approach prevents catastrophic failures while minimizing unnecessary migrations, as blocks are only moved when their age indicates imminent reliability concerns.
Solution Approach 2:
The system designates spare blocks as disposable resources specifically for receiving migrated data from aging blocks. These spare blocks are meant to be used temporarily to extend the life of primary data blocks, and they can be erased and reused after serving their migration purpose, absorbing the wear that would otherwise affect the main storage blocks.
Data Source
AI summary
A reliability control technology for non-volatile memory is shown. A non-volatile memory has a plurality of blocks. For each block, the processor records a time stamp about programming of at least one page in the block. The processor performs a reliability check on the target block that corresponds to a time stamp exceeding a critical time limit and, if the reliability check shows that the target block does not meet a reliability standard, the processor moves data from the target block to a spare space for safe migration.