Deduplication Digest Bucketing for Partial Block Matches

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Solution Overview

Problem

Conventional deduplication schemes require exact matches between hash values, missing opportunities for data reduction due to large differences in hash values even with small differences in blocks, such as varying timestamps or metadata.

Innovation Solution

An improved technique assigns digest values to buckets in a deduplication database, allowing for the identification of both exact and partial matches by generating similarity hash values and performing clustering on sim hashes, enabling deduplication even when blocks contain differing portions of data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If conventional exact-match deduplication schemes are used, then hash value matching is simple and fast, but data reduction opportunities are lost when blocks have minor differences

Engineering Contradiction:
Improvedata reductionVSAvoiddeduplication scheme complexity
Core Design Contradiction:
Loss of substanceVSDevice complexity

Solution Approach 1:

The digest value is segmented into multiple portions, with each portion assigned to a separate bucket. This allows the system to search for partial matches by examining individual bucket portions independently, enabling data reduction for blocks with minor differences while maintaining manageable complexity through localized search operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension to hash matching by dividing the digest into multiple bucket portions and allowing partial matches across these portions. This transforms the traditional single-dimension exact-match approach into a multi-dimensional partial-match system, enabling data reduction for similar blocks without requiring complete hash value matches.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Loss of substance

If similarity hash values and clustering are used to find partial matches, then data reduction is improved, but search complexity and processing time increase

Engineering Contradiction:
Improvedata reductionVSAvoidsearch time
Core Design Contradiction:
Loss of substanceVSLoss of time

Solution Approach 1:

By segmenting the digest into multiple bucket portions and organizing them in a hierarchical structure, the system enables efficient partial-match searches. The segmentation allows the search to proceed through discrete portions rather than requiring exhaustive comparison of entire hash values, reducing search time while maintaining improved data reduction capabilities.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The digest value is pre-divided into multiple bucket portions and organized in advance before the deduplication search begins. This preliminary organization of hash portions enables faster search operations by allowing the system to quickly navigate to relevant buckets and compare only the necessary portions, rather than performing time-consuming full hash comparisons during the deduplication process.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If all buckets are searched for partial matches, then match accuracy is maximized, but processing overhead increases significantly

Engineering Contradiction:
Improvematch accuracyVSAvoidprocessing throughput
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The segmentation of digest into multiple bucket portions allows the system to search through organized segments rather than examining all buckets indiscriminately. This segmentation maintains match accuracy by preserving the ability to identify partial matches while improving processing throughput through structured navigation and reduced search scope.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different bucket portions are treated with different search strategies based on their local characteristics. The system can focus search efforts on buckets with higher likelihood of containing matches, applying varying levels of search intensity to different portions. This local quality approach maintains overall match accuracy while optimizing processing throughput by avoiding exhaustive search of all buckets.

Inventive Principle:
Principle #3Local quality

Data Source

PatentUS11144519B2Deduplicating full and partial block matches
Publication Date: 2021.10.12 EMC IP HLDG CO LLC
  • US11144519B2 patent drawing
  • US11144519B2 patent drawing
  • US11144519B2 patent drawing

AI summary

A technique for performing deduplication traverses a deduplication database and assigns digest values in the database to buckets, where each bucket covers a respective range of digest values. To deduplicate a particular candidate block, the technique generates a digest from the candidate block and searches for the computed digest in a subset of the buckets, where the subset is selected based on the computed digest. If a target block providing an exact match or a suitably close partial match is found in the subset of buckets, the technique effects storage of the candidate block at least in part by providing a reference to the target block.