In-SSD MM OS Cache for Reducing Data Access Latency
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Solution Overview
Problem
Solid state drives (SSDs) experience access latency and transfer time issues due to the need for data to be accessed and transferred from non-volatile memory to a host, which hinders performance in data storage operations.
Innovation Solution
Implementing an In-SSD MM OS cache within the SSD, which uses volatile memory and non-volatile memory in conjunction with an interconnect to cache data, allowing the SSD to direct operations and reduce latency by storing and retrieving data more efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is stored only in non-volatile memory in the SSD, then data storage capacity is improved, but data access latency and transfer time increase
Solution Approach 1:
The memory system is segmented into multiple memory devices with different characteristics (volatile and non-volatile). The volatile memory devices store frequently accessed data for fast access, while non-volatile memory devices store data for long-term retention. This segmentation allows the system to achieve both fast access latency and adequate storage capacity by directing access patterns to appropriate memory segments.
Solution Approach 2:
The volatile memory devices act as an intermediary between the host system and the non-volatile memory devices. When the host requests data, the controller first checks if the data resides in the volatile memory (fast path). If not, it retrieves from non-volatile memory and caches it in volatile memory for future accesses. This intermediary layer absorbs the latency of non-volatile memory while maintaining the appearance of fast access to the host.
2Productivity
If data is transferred from non-volatile memory to host, then data storage function is fulfilled, but transfer time contributes to function performance delay
Solution Approach 1:
The system performs preliminary actions by pre-fetching and caching data from non-volatile memory into volatile memory before the host actually needs it. The controller monitors access patterns and proactively loads data that is likely to be requested soon, so when the host initiates a transfer request, the data is already in the volatile memory ready for immediate transfer, eliminating the need for time-consuming transfers from non-volatile memory.
3Loss of time
If an In-SSD MM OS cache is implemented with volatile and non-volatile memory, then data access latency is reduced, but device complexity increases
Solution Approach 1:
The volatile memory devices serve multiple functions: they act as a high-speed cache for frequently accessed data, as a buffer for data transfer operations, and as temporary storage during garbage collection and wear leveling processes. The non-volatile memory devices provide both long-term data storage and serve as the ultimate backup when volatile memory is full. This multi-functionality reduces the need for separate dedicated components, thereby managing complexity while achieving performance goals.
Data Source
AI summary
The present disclosure includes apparatuses and methods for an operating system cache in a solid state device (SSD). An example apparatus includes the SSD, which includes an In-SSD volatile memory, a non-volatile memory, and an interconnect that couples the non-volatile memory to the In-SSD volatile memory. The SSD also includes a controller configured to receive a request for performance of an operation and to direct that a result of the performance of the operation is accessible in the In-SSD volatile memory as an In-SSD main memory operating system cache.