Snapshot Volume Tree Metadata Sorting for Storage Reclamation

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Solution Overview

Problem

Conventional snapshot management in data storage systems is inefficient in reclaiming storage space for overwritten or deleted data, leading to performance issues due to the lack of effective metadata modification processes.

Innovation Solution

A snapshot management system that maintains a snapshot volume tree with nodes having generation times, allowing for efficient read requests and deletion processes by sorting metadata objects and merging child nodes, thereby optimizing storage space utilization and system performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If conventional techniques are used to reclaim storage space in sparsely-populated snapshots, then storage space can be recovered, but system performance deteriorates due to inefficient metadata modification processes

Engineering Contradiction:

Improvestorage space reclamationVSAvoidsystem performance

Core Design Contradiction:

Loss of substanceVSProductivity

Solution Approach 1:

The system performs preliminary actions by maintaining sorted lists of metadata objects and pre-establishing snapshot volume trees with generation times before deletion operations are needed. This allows the system to quickly identify and reclaim storage space without performing complex metadata modifications during actual deletion operations, thus avoiding performance degradation.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If all data of the source volume is duplicated for snapshot generation, then complete data copies are obtained, but storage space consumption increases significantly

Engineering Contradiction:

Improvesnapshot data completenessVSAvoidstorage space utilization

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The system extracts only the necessary information for snapshot functionality by storing sorted lists of metadata objects that reference original data locations, rather than duplicating entire data sets. The snapshot volume tree structure extracts and stores only the hierarchical relationships and generation time information needed to reconstruct data when required.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces metadata objects as intermediaries between the snapshot structure and actual data storage. These metadata objects contain descriptors that identify data locations and versions, allowing the system to reference original data without duplicating it, thus reducing storage space consumption while maintaining data accessibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If sparsely-populated snapshots storing only uniquely-written data are used, then storage space is optimized, but metadata modification overhead increases

Engineering Contradiction:

Improvestorage space efficiencyVSAvoidmetadata modification overhead

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The system merges related metadata information into a unified snapshot volume tree structure where metadata objects are organized in sorted lists. This consolidation reduces the number of separate metadata modifications required during deletion operations, as changes can be propagated through the tree structure more efficiently than modifying分散 metadata entries.

Inventive Principle:

Principle #5Merging (Combining)

4Ease of manufacture

If snapshots are organized without hierarchical structure, then simple data storage is achieved, but read operation efficiency decreases

Engineering Contradiction:

Improvesnapshot structure simplicityVSAvoidread operation speed

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The system segments the snapshot storage into a hierarchical snapshot volume tree structure with root volumes, child snapshots, and metadata objects organized in sorted lists. This segmentation allows read operations to be directed to specific segments based on the snapshot volume tree, improving read speed by avoiding linear searches through all snapshot data.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11307935B2Management of volume snapshots in a data storage system

Publication Date: 2022.04.19 EMC IP HLDG CO LLC

AI summary

Techniques are provided for managing snapshot volume trees in a snapshot-enabled data storage system. A snapshot management system is configured to maintain a snapshot volume tree for a storage volume of a storage system, wherein the snapshot volume tree comprises a data structure which comprises a plurality of snapshot volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume, wherein the snapshot volume nodes comprise respective generation times which denote times that the respective snapshot volume nodes were created. The generation times are used in conjunction with write times of data items that are written to the snapshot volume nodes to manage snapshot reading and deletion operations.