CXL Memory Buffering for NAND Map Data Initialization
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Solution Overview
Problem
The increasing capacity of NAND flash memory in storage devices requires a high-capacity buffer memory to manage map data, leading to increased costs and limitations in existing systems due to the limited capacity of the buffer memory included in the storage device.
Innovation Solution
The CXL storage system utilizes a shared CXL interface for communication between the host, CXL storage, and CXL memory, allowing the CXL memory to serve as a buffer for map data, thereby alleviating the need for a separate buffer memory within the CXL storage, and enabling the use of a high-capacity CXL memory to manage map data efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capacity of NAND flash memory is increased, then the storage capacity is improved, but the capacity of map data increases requiring a high-capacity buffer memory which increases costs
Solution Approach 1:
The patent extracts the map data buffer function from the storage device and places it in a separate memory device. The storage device no longer needs to include a high-capacity buffer memory for map data, as this function is taken out and performed by an external memory device connected through the CXL interface.
Solution Approach 2:
The patent introduces a separate memory device as an intermediary component that handles map data storage and management. This intermediary memory device acts as a mediator between the host and the storage device, specifically managing the map data that translates logical block addresses to physical block addresses.
2Ease of operation
If a separate buffer memory is included in the storage device, then map data management is improved, but the device complexity and cost increase
Solution Approach 1:
The separate memory device serves multiple functions: it acts as system memory for the host, provides buffer memory for map data management, and can serve as additional storage. This multi-functional approach eliminates the need for dedicated buffer memory within the storage device itself.
Solution Approach 2:
The patent merges the map data buffer function with the system memory function by using the same separate memory device for both purposes. Instead of having separate buffer memory and system memory, a single memory device performs both roles through the CXL interface.
3Reliability
If map data is stored in the storage device, then data retention is improved, but access speed decreases due to limited buffer capacity
Solution Approach 1:
The patent segments the memory system into different functional components: the storage device retains data (including map data) for reliability, while the separate memory device provides high-speed access for active map data management. This segmentation allows both data retention and fast access to coexist.
Solution Approach 2:
The patent adds a new dimension to the memory hierarchy by introducing a separate memory device accessible through the CXL interface. This creates a multi-layered memory structure where data can be accessed at different speeds depending on its location and access pattern.
Data Source
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AI summary
A computing system includes a host, a memory, and a storage device. The memory includes a volatile memory and a memory controller. The storage device is connected with the host through a first interface and includes a nonvolatile memory and a storage controller, the storage device communicating with the host through a first port, communicating with the memory through a second port, and managing the memory. The memory is connected with the storage device through a second interface that is physically separated from the first interface. In an initialization operation, the storage controller sends map data that is stored in the nonvolatile memory to the memory through the second interface. In the initialization operation, the memory controller stores the map data in the volatile memory.