Hybrid SLC MLC SSD Data Progression Architecture

Solution Overview

Problem

The high cost of single-level cell (SLC) solid state drives (SSDs) is prohibitive, while multi-level cell (MLC) SSDs offer lower cell endurance and performance characteristics that are inadequate for many applications, necessitating a balance between the benefits of both technologies.

Innovation Solution

A hybrid SSD comprising a combination of SLC and MLC flash memory, where the SLC memory portion is used for frequent write operations and high endurance needs, and the MLC memory portion is used for read-only or read-mostly data, with data progression techniques to dynamically move data between the two based on access frequency, thereby optimizing cost and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If SLC flash memory is used, then write speed and cell endurance are improved, but cost per megabyte increases

Engineering Contradiction:

Improvecell enduranceVSAvoidcost per megabyte

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The SSD memory is segmented into two distinct portions: a first memory portion using SLC flash memory for high-endurance write operations, and a second memory portion using MLC flash memory for cost-effective storage. This segmentation allows each memory type to be optimized for its specific function, resolving the contradiction between endurance and cost by allocating resources appropriately across different data types.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different quality levels of flash memory are applied to different functional requirements within the SSD. SLC memory with superior write endurance and speed is applied to the first memory portion for frequently written data, while MLC memory with lower cost is applied to the second memory portion for less frequently accessed data. This local quality differentiation resolves the contradiction by matching memory characteristics to specific usage patterns.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If MLC flash memory is used, then cost per megabyte is reduced, but write speed and cell endurance deteriorate

Engineering Contradiction:

Improvecost per megabyteVSAvoidcell endurance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The SSD memory is segmented into two distinct portions: a first memory portion using SLC flash memory for high-endurance write operations, and a second memory portion using MLC flash memory for cost-effective storage. This segmentation allows each memory type to be optimized for its specific function, resolving the contradiction between endurance and cost by allocating resources appropriately across different data types.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different quality levels of flash memory are applied to different functional requirements within the SSD. SLC memory with superior write endurance and speed is applied to the first memory portion for frequently written data, while MLC memory with lower cost is applied to the second memory portion for less frequently accessed data. This local quality differentiation resolves the contradiction by matching memory characteristics to specific usage patterns.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If a hybrid SSD with both SLC and MLC memory is used, then overall cost is reduced while maintaining performance, but device complexity increases

Engineering Contradiction:

Improveoverall costVSAvoidmemory architecture

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges two different flash memory technologies (SLC and MLC) into a single hybrid SSD device, combining their complementary strengths. The SLC portion provides high performance and endurance where needed, while the MLC portion provides cost-effective capacity, achieving an overall cost reduction while maintaining performance through their synergistic combination.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The hybrid SSD architecture provides multi-functionality by handling different types of data operations across different memory portions. The system can perform high-speed writes to SLC memory when needed, while simultaneously utilizing MLC memory for bulk storage, making the single device adaptable to various performance and cost requirements within the same system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9146851B2Single-level cell and multi-level cell hybrid solid state drive

Publication Date: 2015.09.29 DELL INTERNATIONAL LLC

AI summary

A solid state drive (SSD) having a first memory portion comprising SLC flash memory and a second memory portion comprising MLC flash memory. The first memory portion may store read/write data, and the second memory portion may store read-only or read-mostly data. In some instances, the second memory portion may store historical data. The present disclosure also relates to a method of data progression in a hybrid solid state drive having both single-level cell (SLC) flash memory and multi-level cell (MLC) flash memory. The method may include monitoring write operations to the SLC memory, determining whether the frequency of write operations to a particular portion of the SLC memory is below a determined threshold, and moving the data stored in the particular portion of the SLC memory to the MLC memory.