Sequential Unmap Control to Pause Storage Garbage Collection

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Solution Overview

Problem

Inefficient garbage collection processes in data storage devices lead to increased erase and format times due to the risk of invalidating data moved during garbage collection, degrading device performance and user experience.

Innovation Solution

Implement a command analysis system that anticipates unmap commands and pauses garbage collection processes when sequential unmap commands are detected, using criteria such as LBA ranges and data size thresholds to optimize data handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If garbage collection is executed after unmap commands, then data is moved to destination blocks, but subsequent unmap commands may invalidate the moved data causing unnecessary operations

Engineering Contradiction:

Improvedata validityVSAvoidgarbage collection time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary analysis of command sequences to identify patterns of sequential unmap commands before executing garbage collection. By detecting these patterns in advance, the system can prevent unnecessary garbage collection operations from being initiated, thereby avoiding the waste of time and resources described in the contradiction.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If sequential unmap commands are processed immediately, then LBA mappings are invalidated, but garbage collection may move data that will be invalidated causing inefficiency

Engineering Contradiction:

Improvecommand processing speedVSAvoidenergy for unnecessary data movement

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The system implements a feedback mechanism where the analysis of incoming command sequences influences the decision to pause or continue garbage collection. When sequential unmap commands are detected, the system provides feedback to pause garbage collection, preventing energy-wasting data movements. This feedback loop dynamically adjusts garbage collection execution based on real-time command patterns.

Inventive Principle:

Principle #23Feedback

3Loss of energy

If garbage collection is paused for sequential unmap commands, then unnecessary data invalidation is reduced, but command processing delay may occur

Engineering Contradiction:

Improveenergy for unnecessary operationsVSAvoidcommand processing delay

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

The system applies partial pausing of garbage collection only when sequential unmap command patterns are detected, rather than pausing all garbage collection operations universally. This selective approach ensures that energy is conserved only when necessary, while maintaining normal garbage collection performance for other command sequences, thus minimizing overall processing delays.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12499044B2Pausing garbage collection during a sequential unmapping process

Publication Date: 2025.12.16 SANDISK TECHNOLOGIES LLC

AI summary

A data storage device includes a command analysis system that analyzes one or more received commands to determine whether a garbage collection process associated with the one or more received commands should be executed or paused. The command analysis system determines the garbage collection process should be paused when one or more command parameters associated with the received command indicate that the command is an unmap command and is sequential with a previously received unmap command. The garbage collection process is paused until a non-sequential command is received or until an operating state of the data storage device indicates that the garbage collection process should be resumed.