Multi-Bank Flash Write Amplification Reduction
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Solution Overview
Problem
The increasing block sizes in NAND flash memory systems lead to higher write amplification factors due to bank interleaving, which negatively impacts sequential and random write performance, and existing management systems fail to effectively manage this issue.
Innovation Solution
Implementing a multi-bank flash memory system with a controller that manages data through multi-page groups (MPGs), where each MPG is larger than a physical page but smaller than a physical block, and interleaves data writes between banks at an MPG granularity, ensuring that an entire MPG is written to one bank before writing to the next, thereby reducing write amplification and maintaining multi-block parallelism for sequential read and write performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bank interleaving is used to improve sequential and random performance, then performance is improved, but write amplification factor increases
Solution Approach 1:
The patent segments the interleaving operation into two distinct phases: a first phase that performs bank interleaving for improved performance, and a second phase that consolidates data back to original banks to reduce write amplification. This segmentation allows the system to enjoy the benefits of bank interleaving while mitigating its harmful effects on write amplification.
Solution Approach 2:
The patent performs preliminary data consolidation before actual write operations. By consolidating scattered data back to original banks in the second phase before writing, the system prepares the data in an optimized state that reduces the write amplification factor while maintaining the performance benefits of interleaving.
2Stability of the object's composition
If block size is increased to reduce fragmentation, then fragmentation is reduced, but write amplification increases due to partial block writes
Solution Approach 1:
The patent implements dynamic block management where blocks can be dynamically allocated and consolidated based on actual write patterns. Rather than using fixed large blocks that lead to partial writes, the system dynamically adjusts block utilization through its two-phase interleaving process, ensuring that data is written in complete blocks only when necessary, thus reducing write amplification while maintaining low fragmentation.
3Productivity
If page-based management is used to improve write efficiency, then write efficiency is improved, but buffer RAM requirements increase
Solution Approach 1:
The patent applies partial action by implementing buffer RAM only for the portions of data that require caching during the two-phase interleaving process. Rather than allocating buffer RAM for entire blocks or all pages, the system allocates buffer memory only for the active data being interleaved in the first phase and consolidated in the second phase, thus reducing overall buffer RAM requirements while maintaining write efficiency.
Data Source
AI summary
A system and method for reducing write amplification while maintaining a desired level of sequential read and write performance is disclosed. A controller in a multi-bank flash storage device may receive host data for writing to the plurality of flash memory banks. The controller may organize the received data in multi-page logical groups greater than a physical page and less than a physical block and interleave writes of the host data to the memory banks with that striping factor. A buffer RAM is associated with each bank of the multi-bank memory where the buffer RAM is sized as equal to or greater than the size of the multi-page logical group.