Hybrid Cache Memory Segmentation for TBW Optimization
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Solution Overview
Problem
Conventional flash memory devices face challenges in optimizing storage capacity and endurance due to the use of fixed or dynamic SLC caches, which either reduce storage capacity or endurance, and fail to efficiently split the Total Bytes Written (TBW) Spec between static and dynamic caches.
Innovation Solution
A hybrid cache system that includes a static SLC cache and a dynamic XLC cache, where the memory controller dynamically allocates XLC blocks between main memory and the hybrid SLC cache, allowing data to be written in SLC mode to the dynamic cache, and disabling caches based on workload to optimize TBW Spec and endurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed SLC cache is used to temporarily store data for programming into higher capacity memory cells, then memory speed and total bytes written (TBW) are improved, but total storage capacity is reduced
Solution Approach 1:
The cache is segmented into two distinct parts: a fixed SLC cache portion and a dynamic cache portion that can be allocated from the main memory array. This segmentation allows the system to maintain a dedicated high-performance cache for critical operations while using the remaining memory capacity for general storage, resolving the contradiction between cache performance and total storage capacity.
Solution Approach 2:
The cache system transitions from a static fixed-size configuration to a dynamic allocation model where the cache size can be adjusted based on workload requirements. The memory controller dynamically allocates portions of the memory array to serve as cache, allowing the system to optimize between performance and capacity based on actual usage patterns.
2Quantity of substance
If a dynamic SLC cache is used to increase overall storage capacity, then capacity is improved, but endurance capability is reduced
Solution Approach 1:
The cache is divided into a fixed SLC cache portion with high endurance and a dynamic cache portion with lower endurance requirements. By segmenting the cache, the system can allocate the high-endurance SLC portion for critical operations requiring durability while using the dynamic portion for capacity expansion, thus maintaining overall endurance capability while increasing storage capacity.
Solution Approach 2:
Different portions of the cache are assigned different quality characteristics: the fixed SLC cache portion has high endurance and reliability, while the dynamic cache portion has lower endurance requirements. This local differentiation allows the system to optimize each region for its specific function, maintaining overall system endurance while expanding capacity.
3Quantity of substance
If multi-level cells (MLC, TLC, QLC) are used to increase storage capacity, then storage capacity is improved, but write performance and endurance are reduced
Solution Approach 1:
The memory device is segmented into different cell types (SLC, MLC, TLC, QLC) with each serving specific functions. The SLC cache portion provides high-performance write operations, while the MLC/TLC/QLC portions provide high-capacity storage. This segmentation allows the system to optimize both performance and capacity by directing operations to the appropriate cell type.
Solution Approach 2:
Different regions of the memory device are assigned different local qualities: the SLC cache portion has high write performance and endurance, while the MLC/TLC/QLC portions have higher capacity density. This local quality differentiation allows the system to achieve both high performance and high capacity simultaneously by utilizing the appropriate region for appropriate operations.
Data Source
AI summary
Memory devices are disclosed. A memory device may include hybrid cache including single-level cell (SLC) blocks of memory and non-SLC blocks of memory. The memory device may further include a memory controller configured to disable, based on workload of the hybrid cache, a portion of the hybrid cache such that writes are only directed to another, different portion of the cache. Associated methods and systems are also disclosed.