SSD Stream Mapping for Write Amplification Reduction

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Solution Overview

Problem

Multi-stream Solid State Drives (SSDs) face challenges in managing a large number of write stream IDs from applications, exceeding the maximum number of supported streams, leading to inefficiencies in data management and increased write amplification due to internal garbage collection.

Innovation Solution

The SSD evaluates write patterns of each file type/stream ID, assigns actual streams based on similarities and differences in characteristics like write frequency, data size, and Quality of Service requirements, using a module to monitor and map application-assigned stream IDs to SSD-supported stream IDs within a selected window, allowing for dynamic adaptation to changing data loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the SSD supports a limited number of active write streams, then the device complexity is reduced, but the adaptability to handle all files opened by the system deteriorates

Engineering Contradiction:

Improvenumber of active write streamsVSAvoidability to cover all files opened by the system

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments the large number of application-assigned stream IDs into multiple groups, with each group mapped to a separate device stream. This segmentation allows the SSD to handle more logical streams than physical device streams by dividing the stream management into multiple organized segments, resolving the contradiction between limited device streams and the need to support all application files.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mapping layer between application-assigned stream IDs and device stream IDs. This mapping mechanism acts as a mediator that translates a large number of application streams into a limited number of device streams, enabling the system to support more files than the raw number of device streams while maintaining efficient stream management.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If multiple streams are consolidated into a single device stream, then the device complexity is reduced, but the write amplification increases due to internal garbage collection

Engineering Contradiction:

Improvestream management complexityVSAvoidwrite amplification

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent applies local quality by assigning specific characteristics (such as write frequency, data size, and QoS requirements) to different stream groups, and mapping them to appropriate device streams based on these local qualities. This ensures that streams with similar characteristics are grouped together, optimizing garbage collection efficiency and reducing write amplification while maintaining manageable device complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes parameters such as write frequency, data size, and Quality of Service requirements to determine optimal stream grouping and mapping. By evaluating and adjusting these parameters, the system can consolidate streams in a way that minimizes garbage collection overhead and reduces write amplification, balancing device complexity with energy efficiency.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If stream mapping is performed dynamically to adapt to changing data loads, then the adaptability is improved, but the processing time increases due to monitoring and evaluation

Engineering Contradiction:

Improvedynamic adaptation to changing data loadsVSAvoidprocessing time for stream management

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by pre-establishing mapping relationships and organizing streams into groups before actual data writing occurs. This preliminary organization reduces the need for complex real-time decisions during data operations, allowing dynamic adaptation to changing loads while minimizing the time spent on stream management processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements periodic action by updating stream mappings at intervals or based on triggers (such as when certain thresholds are reached), rather than continuously monitoring and re-mapping streams. This periodic approach maintains adaptability to changing data loads while significantly reducing the processing time and overhead compared to continuous dynamic remapping.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11048411B2Method of consolidating data streams for multi-stream enabled SSDs

Publication Date: 2021.06.29 SAMSUNG ELECTRONICS CO LTD

AI summary

A Solid State Drive (SSD) is disclosed. The SSD may include a flash memory to store data and support for a number of device streams. The SSD may also include an SSD controller to manage reading data from and writing data to the flash memory. The SSD may also include a host interface logic, which may include a receiver to receive the commands associated with software streams from a host, a timer to time a window, a statistics collector to determine values for at least one criterion for the software streams from the commands, a ranker to rank the software streams according to the values, and a mapper to establish a mapping between the software streams and device streams.