Elective Garbage Collection for Flash Storage Contention

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Solution Overview

Problem

Solid-state drives designed to conform to hard disk drive standards often struggle to leverage the unique characteristics of flash and other solid-state memories, making it difficult to provide enhanced features or efficiently manage storage space, particularly during upgrades or data migration.

Innovation Solution

A method and system for elective garbage collection in storage memory that monitors and balances storage space across multiple portions of storage memory, using a storage space detector and a garbage collection module to rebalance storage space and adaptively manage data migration based on available space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If garbage collection is performed to rebalance storage space across multiple portions of storage memory, then storage space availability is improved, but flash contention and write amplification increase

Engineering Contradiction:

Improvestorage space availabilityVSAvoidflash contention

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The patent performs garbage collection selectively and partially rather than completely. It targets only specific portions of storage memory that have imbalances, and only when necessary conditions are met (available space threshold not met, imbalance detected). This partial action approach recovers storage space without triggering excessive flash contention that would result from comprehensive garbage collection across all memory portions.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent applies different treatment to different portions of storage memory based on local conditions. It monitors each portion individually and performs garbage collection only in portions that exhibit imbalances and meet specific criteria. This localized approach allows space recovery where needed while avoiding unnecessary operations in balanced portions, thereby reducing overall flash contention.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If conventional garbage collection is performed to recover storage space, then storage efficiency is improved, but system performance deteriorates due to flash contention

Engineering Contradiction:

Improvestorage efficiencyVSAvoidsystem performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent implements a feedback mechanism that continuously monitors storage space availability in each portion of storage memory and system performance metrics. Based on this feedback, it dynamically decides whether to perform garbage collection and which portions to target. This feedback-driven approach ensures garbage collection is triggered only when storage efficiency benefits outweigh performance costs, thereby improving storage efficiency while maintaining system performance.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent makes garbage collection dynamic rather than static. It adapts its behavior based on real-time conditions including storage space availability, imbalance detection, and performance considerations. The system can adjust its garbage collection strategy dynamically, choosing to perform or postpone operations based on current system state, thus balancing storage efficiency gains with performance maintenance.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If data migration is performed during storage system upgrades, then system flexibility is improved, but operation continuity is disrupted

Engineering Contradiction:

Improvesystem flexibilityVSAvoidoperation continuity

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The patent performs preliminary monitoring and evaluation before initiating data migration during upgrades. It checks storage space availability and identifies imbalances in advance, allowing it to plan migration operations that minimize disruption. By preparing and assessing conditions beforehand, the system can execute migrations more smoothly with less impact on operation continuity while still achieving the flexibility benefits of upgraded storage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuity of useful action by performing garbage collection and data migration operations that do not completely halt system operation. It targets specific portions of storage memory and uses selective approaches that allow the system to continue serving requests while rebalancing data. This ensures upgrade-related migrations maintain operation continuity rather than causing complete disruptions.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS10366004B2Storage system with elective garbage collection to reduce flash contention

Publication Date: 2019.07.30 PURE STORAGE INC

AI summary

A method for elective garbage collection in storage memory, performed by a storage system is provided. The method includes monitoring storage space available in each of a plurality of portions of storage memory of a storage system and detecting an imbalance in the storage space available across the plurality of portions of storage memory. The method includes performing garbage collection to rebalance the space available across the plurality of portions of storage memory, responsive to the detecting. A storage system is also provided.