Virtualized File Server Share-Level Rollback with Two-Phase Restore

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Solution Overview

Problem

Existing restoration methods for distributed shares in client-server data protection environments are inefficient and impractical, requiring file-by-file or folder-by-folder client-side restores that incur significant network latency and are not reversible, especially when multiple shares need to be restored synchronously.

Innovation Solution

A server-side restore technique using self-service restore (SSR) snapshots enables share-level restoration directly on a file server through an atomic 2-phase restore-commit transaction, allowing rollback to a last known good (LKG) snapshot, eliminating client involvement and ensuring reversibility and failure safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If client-side restore is used to restore distributed share, then restoration can be performed, but network latency increases and restoration becomes irreversible

Engineering Contradiction:

Improverestoration reversibilityVSAvoidnetwork latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent inverts the traditional client-side restore approach by implementing server-side restore. The file server actively initiates and orchestrates the restore operation by transitioning its own filesystem datasets to a previous snapshot state, eliminating the need for client-initiated round trips and data transfers. This inversion of who performs the restore operation directly resolves the network latency and reversibility issues.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The file server performs self-service restore by autonomously managing its own datasets and snapshots. The server identifies corrupted datasets, selects appropriate snapshots, and executes the restore transition without requiring client involvement. This self-service capability eliminates network dependencies and ensures the restore operation can be completed reliably and reversibly on the server side.

Inventive Principle:

Principle #25Self-service

2Productivity

If file-by-file or folder-by-folder restore is performed, then specific corrupted data can be restored, but restoration of multiple shares becomes impractical and unsynchronized

Engineering Contradiction:

Improverestoration speedVSAvoidsynchronized recovery across shares

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent merges the restore operations for multiple shares into a single coordinated transaction. The file server identifies all shares requiring restoration and executes them simultaneously as part of one atomic operation, transitioning all affected datasets to their respective previous snapshot states in unison. This merging approach enables synchronized recovery across distributed shares while maintaining high productivity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The file server performs preliminary identification and preparation of restore operations before execution. It scans for corrupted datasets, selects appropriate snapshots in advance, and prepares the restore transaction plan. This preliminary action enables the server to execute multiple share restores efficiently in a coordinated manner, achieving both speed and synchronization.

Inventive Principle:

Principle #10Preliminary action

3Loss of time

If server-side restore is implemented, then network latency is reduced and restoration is reversible, but system complexity increases

Engineering Contradiction:

Improvenetwork latencyVSAvoidrestore operation complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent uses snapshots as copies of filesystem datasets to enable reversible restore. Instead of working with the actual data structures, the server creates and transitions references to snapshot copies. This copying mechanism simplifies the restore operation by working with immutable snapshot objects rather than complex data manipulation, reducing the effective complexity while enabling server-side restore capabilities.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS20250335314A1Fast, reversible rollback at share level in virtualized file server

Publication Date: 2025.10.30 NUTANIX INC

AI summary

A server-side restore technique enables restoring of files/folders of a distributed share directly on a file server executing on a node by a file server administrator using self-service restore (SSR) snapshots in accordance with an atomic 2-phase restore-commit transaction. The technique involves share-level restore wherein the entire share state transitions to a previous state of a snapshot, i.e., the granularity of the restore is at the share level (not the file level) for the technique (whereas file level restore granularity is typically used for the client-side restore). The technique is directed to server-side share level restore that allows an “undo” (i.e., rollback) of a previous restore operation into a live snapshot that has become corrupted by a subsequent rollback to a last known good (LKG) snapshot that is uncorrupted. An administration interface may be used to trigger the server-side restore technique for the distributed share.