SSD Write Buffer Control Using Host Unified Write Buffer
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Solution Overview
Problem
The challenge of managing a sufficient number of write buffers in nonvolatile memory systems, particularly in SSDs, is exacerbated by the limited capacity of random access memory, which restricts the number of write destination blocks that can be used simultaneously, limiting scalability and increasing costs.
Innovation Solution
A unified write buffer (UWB) on the host side is utilized, allowing data to be stored temporarily in a predetermined storage area, with the host transmitting write requests to the nonvolatile memory, and the controller managing write destination blocks while notifying the host when data is readable, thereby reducing the need for large-capacity buffers in the memory system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of write destination blocks is increased, then the I/O performance and scalability are improved, but the number of write buffers required increases, which exceeds the limited random access memory capacity
Solution Approach 1:
The patent moves the write buffer functionality from the storage device dimension to the host dimension by utilizing host memory resources. The host CPU performs buffer management operations instead of dedicated buffer memory in the storage device, effectively adding a new dimensional approach to buffer management that bypasses the limited on-device memory capacity.
Solution Approach 2:
The host CPU is made to perform multiple functions: it not only executes application programs but also manages write buffer operations, including data storage, write request generation, and coordination with the storage device. This multi-functionality eliminates the need for dedicated buffer memory in the storage device.
2Adaptability or versatility
If the random access memory capacity in the storage device is increased to provide sufficient write buffers, then the number of available write destination blocks increases, but the cost of the memory system increases
Solution Approach 1:
The write buffer functionality is extracted from the storage device and relocated to the host system. By removing the buffer memory requirement from the storage device, the patent enables more write destination blocks to be available without increasing on-device memory capacity or system cost.
Solution Approach 2:
The host system serves its own buffer management needs by utilizing its existing memory resources and CPU capabilities. The host CPU autonomously manages write data storage and coordinate with the storage device without requiring additional buffer memory in the storage device itself.
Data Source
AI summary
According to one embodiment, a memory system receives, from a host, a write request including a first identifier associated with one write destination block and storage location information indicating a location in a write buffer on a memory of the host in which first data to be written is stored. When the first data is to be written to a nonvolatile memory, the memory system obtains the first data from the write buffer by transmitting a transfer request including the storage location information to the host, transfers the first data to the nonvolatile memory, and writes the first data to the one write destination block.