NAND Die Segmentation for SSD Data Access Stability
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Solution Overview
Problem
Conventional solid state drives face inefficiencies in writing sequential and random data, leading to unstable data access speeds and potential image dropout during tasks like video playback, due to the interference between sequential and random data writing and the time-consuming data merging process.
Innovation Solution
The method involves configuring specific NAND dies for either sequential or random data writing, with memory cells optimized for maximum bit storage levels, allowing for separate and efficient handling of each data type without interference, thereby preventing data mixing and enhancing writing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data merging program is executed to prevent physical erasing units in idle region from being substantially occupied, then the capacity of idle region is maintained above threshold, but a large amount of time is required for execution, causing data writing delay and potential data loss
Solution Approach 1:
The patent segments the storage device into multiple channels, with at least one designated as a sequential channel and others as random channels. This segmentation allows sequential data and random data to be written simultaneously through different channels without interfering with each other, eliminating the need for time-consuming data merging operations while maintaining data safety and idle region capacity.
Solution Approach 2:
The patent introduces a channel selection mechanism as an intermediary that directs sequential data to the sequential channel and random data to random channels. This intermediary prevents data mixing and eliminates the need for data merging programs, thereby resolving the contradiction between data safety and writing time.
2Productivity
If sequential data and random data are written to the same die simultaneously, then writing efficiency is improved, but mutual interference occurs between the two data types
Solution Approach 1:
The patent divides the storage die into multiple independent channels, designating at least one channel for sequential data and other channels for random data. This physical segmentation prevents mutual interference between sequential and random data writing operations while maintaining high writing efficiency through parallel processing.
Solution Approach 2:
The patent assigns different functional qualities to different channels: the sequential channel is optimized for sequential data writing with specific memory cell level configurations, while random channels are optimized for random data writing. This local quality differentiation ensures reliable data writing without interference.
3Reliability
If data merging program is executed frequently to maintain idle region capacity, then the garbage collection threshold is maintained, but the host system experiences unstable operation speed and image dropout
Solution Approach 1:
By segmenting the storage device into sequential and random channels, the patent eliminates the need for frequent data merging operations. Sequential data is written to the sequential channel without interfering with random data in random channels, maintaining system stability and operation speed without image dropout.
Solution Approach 2:
The patent enables continuous writing operations for both sequential and random data simultaneously through different channels, eliminating the interruptions caused by data merging programs. This continuity maintains stable operation speed and prevents image dropout while preserving system reliability.
Data Source
AI summary
A method for accessing data by a solid state disk is provided, which includes steps of: configuring at least one NAND die to be dedicated for writing random data and other NAND dies to be dedicated for writing sequential data; configuring one of the NAND dies dedicated for writing the sequential data to include memory cells each of which is allowed to be used for storing a data stream having the maximum number of bits; configuring one of the NAND dies dedicated for writing the random data to include memory cells each of which is used for storing a data stream having the number of bits that is smaller the maximum number of the bits; and determining the total number of the bits of one of the data streams of the random data written by the NAND dies and accordingly reconfiguring the NAND dies.