SSD Multi-Stream Garbage Collection via Statistical Lifetime Tracking

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Solution Overview

Problem

Conventional Solid State Drives (SSDs) face inefficiencies in garbage collection due to approximated data lifespan assumptions and changing data patterns, leading to poor performance in multi-streaming systems, where data is grouped based on expected life span, resulting in inaccurate timing and increased write amplification factor.

Innovation Solution

Implementing a system that uses statistical models to track the distribution of data lifetimes within streams, allowing for more accurate prediction of data invalidation times and optimizing garbage collection by switching between streams to ensure simultaneous data expiration, thereby reducing the need for valid data relocation during garbage collection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If data is grouped into streams based on approximated life span, then garbage collection should be simplified, but data expiration timing becomes inaccurate leading to poor GC performance

Engineering Contradiction:

Improvegarbage collection complexityVSAvoiddata life span prediction accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system dynamically switches between multiple data streams (first-order streams) based on real-time data characteristics and expiration patterns. Instead of statically assigning data to a single stream based on approximated lifespan, the system adapts stream assignments dynamically, allowing optimal garbage collection timing while maintaining simplified GC operations.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent replaces the mechanical approximation approach (fixed lifespan assumptions) with a statistical analysis system that uses probability distributions and multiple streams to model data expiration behavior. This substitution enables more accurate prediction without requiring complex per-data-point tracking.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of time

If multi-streaming is used to predict data expiration, then garbage collection timing should improve, but write amplification factor increases due to valid data relocation

Engineering Contradiction:

Improvegarbage collection timing accuracyVSAvoidwrite amplification factor

Core Design Contradiction:

Loss of timeVSLoss of substance

Solution Approach 1:

The system performs preliminary statistical analysis and stream assignment before garbage collection is needed. By pre-grouping data into multiple streams with different expiration characteristics and using statistical models to predict expiration times, the system prepares optimal collection timing in advance, reducing the need for emergency valid data relocation and thus lowering write amplification.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the parameter representation from single approximated lifespan values to multiple streams with statistical distribution parameters. This allows more accurate prediction of data expiration times, enabling garbage collection to be performed at optimal moments when fewer valid data relocation operations are needed, thereby reducing write amplification factor.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If streams are assigned based on similar attributes, then data behavior should be predictable, but changing data patterns violate timing assumptions

Engineering Contradiction:

Improvedata stream consistencyVSAvoiddata pattern adaptability

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The system segments data into multiple first-order streams based on different attributes and expiration patterns. Instead of relying on a single stream assignment that becomes invalid when patterns change, the segmentation into multiple streams allows the system to adapt to changing data patterns by selecting or switching between appropriate streams, maintaining both consistency within streams and adaptability across streams.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9898202B2Enhanced multi-streaming though statistical analysis

Publication Date: 2018.02.20 SAMSUNG ELECTRONICS CO LTD

AI summary

A system and method for using a Solid State Drive (SSD) (505) are described. Reception circuitry (510) may receive write requests (1610, 1615, 1620, 1625) and invalidate requests (1630, 1635, 1640) from a first stream (305, 320, 335, 350). The write requests (1610, 1615, 1620, 1625) may request that data be written to storage (520) on the SSD (505); invalidate requests (1630, 1635, 1640) may invalidate data written to the storage (520). A statistics calculation logic (1705) may calculate statistics (1410, 1415, 1510) for the stream based on the write requests (1610, 1615, 1620, 1625) and the invalidate requests (1630, 1635, 1640). A performance logic (1710) may use the calculated statistics (1410, 1415, 1510) to improve the performance of the SSD (505).