VolumeGroupSnapshot Support Design Implementation

Based on Velero PR: #8778

Related Issue: #8447

Overview

This epic implements VolumeGroupSnapshot (VGS) support in OADP/Velero, extending the platform to support grouped snapshots using the Kubernetes VolumeGroupSnapshot API. This feature allows users to group PVCs by specifying a label key, ensuring that all related PVCs are snapshotted together for data consistency.

Key Features

Grouped PVC Snapshots

• Group PVCs using label-based selection
• Ensure atomic snapshot operations for related volumes
• Maintain data consistency across grouped volumes
• Support for application-aware backup strategies

Workflow Integration

• Updates existing backup workflows to handle VGS objects
• Seamless integration with current Velero backup processes
• Enhanced backup plugins for VGS support
• Restore workflow compatibility (VGS not required on restore)

Technical Implementation

Backup Workflow Updates

• Detection and grouping of PVCs based on specified labels
• Creation of VolumeGroupSnapshot objects during backup
• Integration with existing volume snapshot mechanisms
• Plugin architecture enhancements for VGS handling

Plugin Development

• New backup plugins for VGS object processing
• Updates to existing volume snapshot plugins
• Restore plugin compatibility considerations
• Backwards compatibility with non-VGS environments

Design Considerations

Label-Based Grouping

• Flexible label key specification for PVC grouping
• Support for multiple grouping strategies
• Validation of grouped PVC relationships
• Error handling for incomplete groups

Data Consistency

• Atomic snapshot operations across grouped volumes
• Point-in-time consistency guarantees
• Handling of cross-volume dependencies
• Application quiescing considerations

Backwards Compatibility

• Non-breaking changes to existing workflows
• Graceful degradation in environments without VGS support
• Migration path for existing backup configurations
• Compatibility with older Kubernetes versions

Performance and Requirements

Performance Considerations

• Optimized snapshot creation for grouped volumes
• Reduced backup time through parallel operations
• Resource utilization optimization
• Scalability with large volume groups

Requirements

• Kubernetes VolumeGroupSnapshot API availability
• Compatible CSI drivers with VGS support
• Appropriate RBAC permissions for VGS operations
• Storage backend support for grouped snapshots

Testing Strategy

• Unit tests for VGS workflow components
• Integration tests with various CSI drivers
• End-to-end testing with real applications
• Performance benchmarking for grouped operations
• Backwards compatibility validation

Target Release

• Implementation target: OADP 1.6.0
• Merged upstream: June 4, 2025

Benefits

• Enhanced data consistency for multi-volume applications
• Improved backup reliability for complex workloads
• Simplified backup configuration for grouped resources
• Better support for stateful applications with multiple volumes