Storage Garbage Collection Balancing Wear and Performance

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Solution Overview

Problem

Existing storage systems face challenges in achieving uniform wear-leveling across solid state memory modules, leading to the formation of 'hot spots' due to inadequate garbage collection methods that do not consider both the usage of data blocks and program/erase cycle values.

Innovation Solution

A garbage collection method that selects blocks for processing based on both the current program/erase cycle value and the percentage of used space, balancing wear-leveling and user write performance by prioritizing blocks with low P/E cycle values and minimum used space, ensuring even distribution of wear across modules.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If garbage collection prioritizes only wear-leveling (lowest P/E cycle blocks), then uniform wear distribution is improved, but user write performance deteriorates due to excessive data copying from frequently used blocks

Engineering Contradiction:
Improvewear-leveling uniformityVSAvoiduser write performance
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent changes the selection parameters for garbage collection from solely P/E cycle count to a composite metric that includes both P/E cycle count and data block usage frequency. This allows the system to balance wear-leveling with performance by adjusting which blocks are selected for collection based on multiple parameters simultaneously.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system dynamically adjusts garbage collection behavior based on real-time monitoring of block usage patterns and wear levels. By continuously adapting the collection strategy based on current system state, it optimizes the balance between wear distribution and write performance without manual intervention.

Inventive Principle:
Principle #15Dynamics

2Productivity

If garbage collection prioritizes only blocks with minimum used space, then collection efficiency is improved, but wear-leveling deteriorates as low P/E cycle blocks remain unused

Engineering Contradiction:
Improvecollection efficiencyVSAvoidwear-leveling uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent modifies the block selection criteria by incorporating both space utilization and wear level parameters. Instead of using a single parameter (space used), it uses a combination of parameters to select blocks that need both space reclamation and wear balancing, achieving dual objectives simultaneously.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system proactively identifies and collects data from blocks that are both nearly full and have low P/E cycle counts, preventing future wear imbalances before they occur. This preliminary action on selected blocks avoids the need for reactive wear-leveling operations later.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If comprehensive monitoring of both P/E cycle values and data usage is implemented, then wear-leveling and performance optimization are improved, but system complexity increases

Engineering Contradiction:
Improvewear-leveling uniformityVSAvoidgarbage collection system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The garbage collection system is designed to perform multiple functions simultaneously: wear-leveling, space reclamation, and performance optimization. By making the GC system multi-functional through intelligent block selection, it reduces the need for separate mechanisms for each objective, thereby managing complexity while achieving multiple goals.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses its existing monitoring infrastructure to gather both P/E cycle and usage data, then leverages this information to make autonomous decisions about block selection. This self-service approach allows comprehensive monitoring without proportionally increasing system complexity, as the same data collection mechanisms serve multiple purposes.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS10289548B1Method and system for garbage collection in a storage system which balances wear-leveling and performance
Publication Date: 2019.05.14 EMC IP HLDG CO LLC
  • US10289548B1 patent drawing
  • US10289548B1 patent drawing
  • US10289548B1 patent drawing

AI summary

In general, embodiments of the technology relate to a method for managing data. The method includes, in response to initiating garbage collection on a storage appliance, selecting a first block from the plurality of blocks based, at least in part, on a selection frequency; and performing a garbage collection operation on the first block to generate a first erased block in the storage appliance.