Snapshot Set Metadata for Storage Volume Consistency Groups

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Solution Overview

Problem

Conventional data storage systems face limitations in adding or removing storage volumes from consistency groups without deleting snapshots or snapshot sets, which reduces the amount of consistent data available for recovery in case of failures or disasters.

Innovation Solution

The implementation of expanded metadata for snapshots, including a snapshot set identifier and consistency group identifier, and enhanced data structures with a snapshot set list and pointers to storage volume lists, allows storage volumes to be added or removed from consistency groups without deleting existing snapshots or snapshot sets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If storage volumes are added to or removed from consistency groups in conventional data storage systems, then the consistency group structure is updated, but snapshots and snapshot sets must be deleted first which reduces data availability for recovery

Engineering Contradiction:

Improveability to add/remove storage volumes from consistency groupsVSAvoidamount of consistent data available for recovery

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent segments the consistency group management by introducing a snapshot set level abstraction between individual snapshots and the consistency group. This allows storage volumes to be added or removed from consistency groups without requiring deletion of snapshots, as the snapshot set structure maintains the relationships independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces snapshot sets as an intermediary layer that mediates between individual snapshots and consistency groups. The snapshot set acts as a container that can be associated with consistency groups without requiring direct modification of individual snapshots when volumes are added or removed.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If snapshots are deleted before adding storage volumes to consistency groups, then the consistency group can be updated, but the amount of consistent data available for recovery is reduced

Engineering Contradiction:

Improveprocess of adding storage volumes to consistency groupsVSAvoiddata recovery capability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent establishes snapshot sets and their associations with consistency groups in advance, creating a predefined structure that allows future additions or removals of storage volumes without requiring deletion of snapshots. This preliminary structuring enables operational flexibility while preserving data.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a logical copy or representation of snapshot relationships through the snapshot set structure, which can be modified (added/removed volumes) without affecting the actual snapshot data. This allows operational changes while preserving the original snapshot content for recovery purposes.

Inventive Principle:

Principle #26Copying

3Adaptability or versatility

If snapshot sets are deleted before removing storage volumes from consistency groups, then the consistency group structure is updated, but consistent data is lost

Engineering Contradiction:

Improveability to remove storage volumes from consistency groupsVSAvoidconsistent data availability

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent segments the relationship management by introducing snapshot sets as an independent layer. This segmentation allows the consistency group structure to be modified (adding or removing volumes) without requiring deletion of the underlying snapshot data, as the snapshot set structure maintains the associations independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts the snapshot management functionality from the consistency group operations by introducing snapshot sets as a separate controllable entity. This extraction allows consistency group modifications without necessarily affecting snapshot retention, enabling flexible volume management while preserving data for recovery.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS10838825B2Implementing snapshot sets for consistency groups of storage volumes

Publication Date: 2020.11.17 EMC IP HLDG CO LLC

AI summary

Techniques for implementing snapshot sets for consistency groups of storage volumes in data storage systems. For each snapshot in a snapshot set of a consistency group, metadata is expanded to include a snapshot set identifier, and a consistency group identifier. The data structure of the consistency group is enhanced to include a snapshot set list, which includes the snapshot set identifier(s) of the consistency group, and a pointer to a storage volume list that contains names of storage volumes with snapshots in the snapshot set(s). By expanding the metadata of each snapshot in a snapshot set, and enhancing the data structure of each consistency group with snapshot set(s), relationships between snapshots, snapshot sets, consistency groups, and storage volumes can be readily maintained, allowing storage volumes to be added to and/or removed from consistency groups without having to delete snapshots of the storage volumes and/or snapshot sets of the consistency groups.