Host-System Address Map Caching for SSD Performance
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Solution Overview
Problem
Solid-state drives (SSDs) face performance and longevity issues due to insufficient DRAM capacity to cache the entire address map, leading to increased swapping times and write operations in NAND flash memory.
Innovation Solution
Caching a portion of the address map in the host system's memory, allowing the SSD to swap out and load required portions from the host system's memory instead of NAND flash, reducing swapping times and write operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the entire address map is cached in DRAM, then data access performance is improved, but DRAM capacity requirements increase significantly
Solution Approach 1:
The address map is divided into multiple segments or portions that can be independently managed. Instead of loading the entire address map into DRAM, only the currently needed portions are cached in DRAM while other portions remain in NAND flash memory. This segmentation allows the system to maintain high performance for active operations while minimizing DRAM usage.
Solution Approach 2:
The patent introduces a hierarchical memory architecture that adds another dimension to the traditional single-level caching approach. By organizing the address map across multiple memory levels (DRAM cache and NAND flash storage) with different access characteristics, the system can simultaneously optimize for both speed and capacity constraints.
2Quantity of substance
If address map portions are swapped from NAND flash memory, then DRAM capacity requirements are reduced, but swapping time increases
Solution Approach 1:
The system performs preliminary actions by pre-loading address map portions into DRAM before they are actually needed, or by maintaining multiple copies of frequently accessed portions. This anticipatory approach reduces the actual swapping time when address translations are required, as the data is already in the faster DRAM memory when needed.
Solution Approach 2:
The patent implements mechanisms to maintain continuous useful action by keeping address map portions in DRAM as long as they are needed, and by overlapping data transfer operations with processing operations. This minimizes idle time and ensures that address translations can proceed without interruption once the data is in DRAM.
3Quantity of substance
If address map is stored in NAND flash memory, then DRAM capacity is reduced, but write operations increase frequency
Solution Approach 1:
The patent extracts the most frequently accessed or currently needed portions of the address map from NAND flash memory and places them in DRAM. This extraction reduces the frequency of write operations to NAND flash, as updates to the active address map portions can be performed in the faster DRAM without immediately propagating changes to the NAND flash storage.
Data Source
AI summary
A system having non-volatile media, a volatile memory, and a controller configured to process requests from a host system to store data in the non-volatile media or retrieve data from the non-volatile media. The non-volatile media has a quantity of memory units and stores an address map that defines logical addresses used in the requests in terms of physical addresses of the memory units in the non-volatile media. The host system has a memory connected to the system via a communication channel. The system has a cache manager that stores a first portion of the address map in the volatile memory of the system and a second portion of the address map in the memory of the host system. In response to an operation that uses a logical address defined in the second portion, the cache manager retrieves the second portion of the address map from the memory.