Pseudo Snapshot Resynchronization via Intercept Tracking Logs

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing data replication and snapshot creation techniques in storage networks can be disruptive to client access and may cause data divergence between storage clusters, especially during failover and switchover operations.

Innovation Solution

The implementation of pseudo common snapshot creation and utilization, which allows for non-disruptive snapshot creation by logging incoming client write requests and using intercept tracking logs to manage data differences between storage clusters, thereby maintaining synchronous replication relationships.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional snapshot creation is implemented during synchronous replication, then data consistency between storage clusters is maintained, but client data access is disrupted and write requests are blocked

Engineering Contradiction:

Improvedata consistencyVSAvoidclient data access

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system performs preliminary actions by creating intercept tracking logs that record incoming client write requests before snapshot creation. These logs capture the state of data at the time of snapshot initiation, allowing the snapshot to be created without blocking client writes. The preliminary logging ensures data consistency is captured while avoiding disruption to client operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

An intercept tracking log acts as an intermediary mechanism between client write requests and the snapshot creation process. The log records write operations without requiring them to complete or be blocked, mediating between the need for consistent snapshot data and the need for continuous client access. This intermediary allows both snapshot creation and client writes to proceed concurrently.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If snapshot creation blocks client write requests to ensure consistency, then data divergence is prevented, but latency and client data access disruption increase

Engineering Contradiction:

Improvedata consistencyVSAvoidclient access latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary logging of client write requests to intercept tracking logs before snapshot creation begins. This preliminary action captures the necessary consistency information without requiring client writes to wait, thereby preventing data divergence while avoiding the time loss associated with blocking client access during snapshot operations.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If non-disruptive snapshot creation is implemented without intercept tracking logs, then client access continues uninterrupted, but data divergence occurs between storage clusters

Engineering Contradiction:

Improveclient data accessVSAvoiddata consistency

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The intercept tracking log serves as an intermediary that records client write requests during snapshot creation. This intermediary mechanism ensures that even though client access continues uninterrupted, the system maintains an accurate record of data changes, preventing data divergence between the primary and secondary storage clusters by providing a reference for consistency verification.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If traditional replication methods are used during failover, then data redundancy is maintained, but resynchronization is complex and time-consuming

Engineering Contradiction:

Improvedata redundancyVSAvoidresynchronization process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Intercept tracking logs are created and maintained as a preliminary structure that records the state of data at specific points in time. During failover and resynchronization operations, these pre-created logs provide a ready reference that simplifies the resynchronization process, eliminating the need for complex real-time comparison and data transfer operations between clusters.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250053316A1Low overhead resynchronization snapshot creation and utilization

Publication Date: 2025.02.13 NETAPP INC

AI summary

One or more techniques and/or computing devices are provided for resynchronization. For example, a request may be received to create pseudo snapshots of a first consistency group, hosted by a first storage controller, and a second consistency group, hosted by a second storage controller, having a synchronous replication relationship with the first consistency group. Incoming client write requests are logged within an intercept tracking log at the first storage controller. After a first drain without hold of incoming write requests is performed, a first pseudo common snapshot of the second consistency group is created. After a second drain without hold of incoming write operations is performed, a second pseudo common snapshot of the first consistency group and the intercept tracking log is created. The pseudo snapshots and the intercept tracking log (e.g., indicating a delta between the pseudo snapshots) are used to resynchronize the first and second consistency groups.