Garbage Collection Locking for Deduplicated Data Segment Protection

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Solution Overview

Problem

Conventional deduplicated data systems face challenges in efficiently performing garbage-collection operations, particularly in preventing the inappropriate deletion of newly added data segments and recovering unwanted deletions, due to the temporary nature of references and compatibility issues with certain garbage collection subsystems.

Innovation Solution

The systems and methods described involve identifying segment objects added during a garbage-collection process, locking them to prevent removal, and unlocking them after the process is complete, using techniques such as adding references to a locked segment object map, to ensure accurate data management and prevent unwanted deletions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If temporary indicators are attached to all newly added data segments to prevent premature deletion, then the reliability of data segment retention is improved, but the device complexity and performance overhead increase significantly

Engineering Contradiction:
Improvedata segment retention accuracyVSAvoidgarbage collection mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary actions by locking segment objects before the garbage collection process begins and maintains these locks throughout the garbage collection operation. This preliminary locking prevents the need for temporary indicators on data segments, as the locks proactively protect newly added segments from premature deletion without requiring additional metadata or complex tracking mechanisms.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces locks as an intermediary mechanism between the garbage collection subsystem and segment objects. These locks act as mediators that prevent direct interaction between the garbage collection process and newly added segment objects, thereby protecting the segments without requiring temporary indicators or modifying the segment objects themselves.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the garbage collection subsystem examines all data segments to identify unreferenced segments for deletion, then the productivity of space reclamation is improved, but the risk of incorrectly deleting newly added referenced segments increases

Engineering Contradiction:
Improvegarbage collection efficiencyVSAvoiddata segment deletion accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system applies preliminary anti-action by locking segment objects that are added during the garbage collection process. This locking mechanism counteracts the potential harmful effect of the garbage collection subsystem incorrectly deleting these segments. The locks are applied in advance and maintained throughout the garbage collection operation, preventing any deletion attempts on locked segments regardless of their reference status.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The patent implements a feedback mechanism where the system continuously monitors for newly added segment objects during the garbage collection process. When new segments are detected, the system provides feedback by locking these segments immediately, ensuring they are protected from deletion. This feedback loop maintains the integrity of the garbage collection process while protecting newly added data.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If conventional garbage collection methods are used without locking mechanisms, then the ease of operation is maintained, but unwanted deletions of newly added segment objects occur

Engineering Contradiction:
Improvegarbage collection simplicityVSAvoidsegment object deletion accuracy
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system implements self-service by having the garbage collection subsystem automatically lock segment objects that are added during the garbage collection process. This automatic locking mechanism protects newly added segments without requiring manual intervention or complex configuration. The subsystem serves itself by monitoring for new segments and applying locks autonomously, maintaining ease of operation while improving deletion accuracy.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2545435B1Systems and methods for garbage collection in deduplicated data systems
Publication Date: 2016.12.07 GEN DIGITAL INC
  • EP2545435B1 patent drawingFigure 1
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  • EP2545435B1 patent drawingFigure 3

AI summary

A computer-implemented method for garbage collection in deduplicated data systems may include: 1) identifying a deduplicated data system, 2) identifying at least one segment object added to the deduplicated data system during a garbage-collection process of the deduplicated data system, 3) locking the segment object to prevent removal of the segment object by the garbage-collection process, and 4) unlocking the segment object after the garbage-collection process. The method may allow a small possibility of incorrectly removing useful segment objects. The method may also verify data objects during the garbage-collection process and recover incorrectly removed segment objects. Various other methods, systems, and computer-readable media are also disclosed.