Shadow Volume Data Preservation for Copy Service Reliability
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Solution Overview
Problem
Data loss occurs in target volumes during copy service functions due to user errors in selecting incorrect target volumes, despite existing safeguards, leading to overwriting and loss of valuable data, which is difficult to manage and often results in storing unused data to avoid loss.
Innovation Solution
A method that automatically creates a shadow volume in a different address space to receive data overwritten on the target volume, establishing a point-in-time copy relationship to preserve data, thereby preventing data loss by storing original data in the shadow volume if an error occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If warning messages are presented to users before establishing copy relationships, then users may be alerted to potential data loss, but these messages become cumbersome and are frequently ignored
Solution Approach 1:
The system automatically creates shadow volumes without requiring user action. The storage system monitors copy operations and autonomously preserves target volume data by creating shadow copies in the background, eliminating the need for users to manually back up data or respond to warnings.
Solution Approach 2:
A shadow volume acts as an intermediary between the source and target volumes. It receives and stores overwritten data from the target volume, serving as a safety buffer that prevents data loss while allowing the primary copy operation to proceed without interruption or user intervention.
2Reliability
If administrators add storage capacity to maintain backup data, then data loss is avoided, but large quantities of unused data are stored and maintained
Solution Approach 1:
Instead of maintaining continuous backups of entire volumes, the system creates shadow volumes only for the specific data blocks that are actually overwritten. This localized approach preserves data only where needed, minimizing storage consumption while maintaining reliability.
Solution Approach 2:
The system automatically discards shadow volume data once it is no longer needed. When the copy relationship is terminated or the shadow volume age exceeds a threshold, the shadow data is automatically deleted, preventing accumulation of unused backup data and optimizing storage utilization.
3Reliability
If manual backup procedures are implemented, then data can be preserved, but managing thousands of volumes becomes difficult and error-prone
Solution Approach 1:
The storage system performs automatic shadow volume creation and management without user intervention. The system self-monitors copy operations, automatically creates shadow copies when needed, and manages the lifecycle of shadow volumes, eliminating the complexity of manual backup management across thousands of volumes.
Solution Approach 2:
The shadow copy mechanism provides universal protection across all copy operations in the storage system. A single automated system handles backup creation, maintenance, and deletion for all volumes, replacing numerous individual manual backup procedures with one unified multi-functional solution.
Data Source
AI summary
A method for preventing data loss in target volumes of copy service functions is disclosed. In one embodiment, such a method includes detecting a copy service function that copies data from a source volume to a target volume. The method automatically creates, in a different address space than the source volume and target volume, a shadow volume to receive data overwritten on the target volume. The method further automatically establishes a point-in-time copy relationship between the target volume and the shadow volume to preserve data on the target volume as writes are received thereto. A corresponding system and computer program product are also disclosed.