Storage Controller Scheduling for Uneven Word Line Program Times
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Solution Overview
Problem
The increasing size of memory blocks in non-volatile memory devices leads to varying program times between word lines, affecting data reliability and performance, and the erase operations cause peak power consumption.
Innovation Solution
A storage device and method that includes a storage controller to manage program and erase operations across multiple non-volatile memory devices, utilizing a word line table to allocate memory blocks based on consistent program times and distribute erase operations, ensuring interleaving operations and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of memory block increases to increase capacity, then integration density is improved, but difference in program time between word lines increases
Solution Approach 1:
The memory block is divided into multiple sub-blocks, each containing a specific range of word lines. The controller manages programming operations on a per-sub-block basis, allowing fine-grained control over program times. This segmentation enables the system to handle the large memory block capacity while maintaining program time consistency through selective sub-block programming.
Solution Approach 2:
The controller dynamically adjusts programming parameters such as voltage levels and pulse widths based on the specific word line being programmed. By monitoring and adapting these parameters in real-time, the system compensates for variations in program time across different word lines within the same memory block, thereby maintaining consistent programming performance despite the increased block size.
2Reliability
If erase operations are performed on memory blocks, then data reliability is improved, but peak power consumption increases
Solution Approach 1:
The erase operation is segmented to target only specific sub-blocks that require erasure rather than entire memory blocks. The controller identifies and erases only the necessary sub-blocks containing invalid or stale data, significantly reducing the power consumption associated with erase operations while maintaining data reliability through selective rejuvenation of memory regions.
Solution Approach 2:
The system performs preliminary identification of sub-blocks requiring erasure before executing the erase operation. By pre-processing to determine which sub-blocks need erasure based on wear leveling metrics and data validity, the system avoids unnecessary erase operations on already healthy sub-blocks, thereby reducing peak power consumption while ensuring data reliability is maintained where needed.
Data Source
AI summary
A storage device includes a plurality of non-volatile memory devices and a storage controller configured to generate program commands and first addresses corresponding to a plurality of word lines included in a first super block based on a sequential write request from a host, determine whether to allocate at least one sub-memory block included in a second super block based on data of a word line table which indicate word lines having a relatively small program time and the first addresses, and generate at least one erase command and at least one second address corresponding to the allocated at least one sub-memory block for performing an erase operation.