Metadata Deduplication for Storage Memory Reduction

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Solution Overview

Problem

Storage systems face inefficiencies in memory usage due to storing duplicate data chunks during data management operations, leading to unnecessary memory waste as they store metadata for all data chunks, even when only a single copy is likely to be retained over time.

Innovation Solution

Implementing a post-processing metadata conversion process that deduplicates data chunks by identifying and removing entries for chunks not referenced by a threshold number of objects and modifying chunk identifiers from SHA-1 hash values to shorter representations, thereby reducing memory usage in the hot storage tier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the storage system stores metadata for all data chunks to enable complete tracking and retrieval, then data retrieval reliability is improved, but memory usage increases significantly due to duplicate chunks

Engineering Contradiction:
Improvedata retrieval reliabilityVSAvoidmemory usage
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent extracts and removes duplicate data chunk entries from the metadata store, keeping only unique chunk references. This selective removal reduces memory usage while preserving the ability to retrieve all necessary data chunks through the remaining unique metadata entries.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the state of metadata by transitioning from storing complete metadata for all chunks (including duplicates) to storing condensed metadata that references unique chunks. This parameter change in metadata representation reduces memory consumption while maintaining retrieval capability.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If the storage system performs in-line deduplication to remove duplicate data chunks during ingestion, then storage utilization is improved, but processing time and computational resources increase

Engineering Contradiction:
Improvestorage utilizationVSAvoidprocessing time
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

The patent performs deduplication as a preliminary action during the data ingestion process rather than as a separate subsequent operation. By identifying and removing duplicate chunks during ingestion, the system prepares the metadata store in advance, reducing future memory usage without requiring a separate deduplication pass.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuous deduplication action during data ingestion operations, ensuring that duplicate chunks are identified and removed as they are being ingested. This continuous process eliminates the need for separate batch deduplication operations, optimizing both storage utilization and processing efficiency.

Inventive Principle:
Principle #20Continuity of useful action

3Reliability

If the storage system uses SHA-1 hash values for chunk identifiers to ensure data integrity, then data security is improved, but memory usage increases due to the length of the identifiers

Engineering Contradiction:
Improvedata securityVSAvoidmemory usage
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential identifying information from the full SHA-1 hash values, storing condensed chunk identifiers in the metadata. This selective extraction reduces the memory footprint of metadata entries while maintaining the ability to uniquely identify and retrieve data chunks.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameter of chunk identifier representation from full SHA-1 hash values (20 bytes) to condensed identifiers (4-8 bytes). This parameter change significantly reduces memory usage in the metadata store while preserving data integrity through the use of reference tables that map condensed identifiers to full hashes when needed.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS12164799B2Reducing memory usage in storing metadata
Publication Date: 2024.12.10 COHESITY INC
  • US12164799B2 patent drawing
  • US12164799B2 patent drawing
  • US12164799B2 patent drawing

AI summary

Data associated with a source system is ingested. After the data is ingested, a post-processing metadata conversion process is performed including by selecting an entry of a chunk metadata data structure and determining that a data chunk associated with the selected entry is not referenced by at least a threshold number of objects. In response to determining that the data chunk associated with the selected entry is not referenced by at least the threshold number of objects, metadata of a tree data structure node corresponding to a chunk identifier associated with the data chunk is updated to store a reference to a chunk file storing the data chunk and the selected entry is removed from the chunk metadata data structure.