NAND-to-NAND Data Copying for SSD Write Bandwidth

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Solution Overview

Problem

Solid state drives (SSDs) face challenges in managing the limited storage capacity of faster single-level cell (SLC) blocks by efficiently transferring data to slower quad-level cell (QLC) blocks, which is essential for preventing SLC block overflow and optimizing write bandwidth.

Innovation Solution

The SSD configures NAND memory into SLC and QLC blocks, using internal data movements and specific command sets to transfer data directly from SLC blocks to QLC blocks, bypassing external SRAM and optimizing write operations through the use of existing and new set feature commands for efficient data copying.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If data is transferred from SLC blocks to QLC blocks using external SRAM, then data copying can be performed, but write bandwidth is reduced due to external data transfer

Engineering Contradiction:

Improvestorage capacityVSAvoidwrite bandwidth

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The patent extracts the data transfer operation from the external SRAM pathway and relocates it to an internal NAND-to-NAND copy operation. By using the set feature command to copy data directly between SLC and QLC blocks within the NAND memory, the system eliminates the bottleneck of external SRAM transfers, thereby maintaining high write bandwidth while achieving the storage capacity migration.

Inventive Principle:

Principle #2Taking out (Extraction)

2Productivity

If SLC blocks are used for high-speed storage, then write performance is improved, but storage capacity is limited due to smaller block size

Engineering Contradiction:

Improvewrite performanceVSAvoidstorage capacity

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent segments the NAND memory into two distinct types of blocks: SLC blocks for high-speed write operations and QLC blocks for high-density storage. This segmentation allows the system to leverage the performance advantages of SLC blocks for active data handling while utilizing the capacity advantages of QLC blocks for long-term storage, effectively resolving the trade-off between speed and capacity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a copying mechanism where data is periodically copied from SLC blocks to QLC blocks using the set feature command. This copying operation enables the system to maintain the performance benefits of SLC blocks for active data while migrating data to QLC blocks for capacity expansion, allowing both performance and capacity requirements to be satisfied simultaneously.

Inventive Principle:

Principle #26Copying

3Quantity of substance

If data is copied sequentially from SLC to QLC blocks, then data transfer can be completed, but copying time is increased

Engineering Contradiction:

Improvedata transfer completionVSAvoidcopying time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The patent implements continuous data copying from SLC blocks to QLC blocks through periodic set feature commands. Rather than completing the entire copy operation sequentially, the system maintains continuous copying action, where data is copied in ongoing batches as SLC blocks fill up. This continuous approach minimizes the loss of time by keeping the copying process active and progressive rather than completing it in a single sequential pass.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS10430108B2Concurrent copying of first and second subsets of pages from media such as SLC NAND to media such as QLC or MLC NAND for completion of copying of data

Publication Date: 2019.10.01 INTEL NDTM US LLC

AI summary

A determination is made that data has to be moved internally within a non-volatile memory from a plurality of pages of a first type of storage media to a page of a second type of storage media. A first subset of the plurality of pages is copied from the first type of storage media to the page of the second type of storage media. Concurrently with the copying of the first subset of the plurality of pages, a second subset of the plurality of pages is copied from the first type of storage media to the page of the second type of storage media. In response to completion of the copying of the first subset and the second subset of the plurality of pages, it is determined that the copying of the data from the first type of storage media to the second type of storage media has completed.