Point-in-Time Copy Cascade Restoration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing point-in-time copy solutions in computer storage systems face challenges when dealing with cascaded configurations, particularly in managing dependencies between data targets, which can lead to inefficient storage allocation and increased metadata usage, and the cleaning process becomes cumbersome, especially when using space-efficient volumes.
Innovation Solution
A method for managing storage volumes in a point-in-time copy cascade that detects corruption in the first target volume, creates a new target volume from a secondary point-in-time target volume, redirects I/O operations, and restores the original target volume, allowing for efficient storage management and reduced cleaning operations by utilizing space-efficient volumes and incremental mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a snapshot copy is used to create a point-in-time copy, then storage space is reduced through thin provisioning, but the target disk remains dependent on the source disk and cannot be restored independently if corrupted
Solution Approach 1:
The patent segments the restoration process into multiple phases: detecting corruption, creating a new target volume from the corrupted snapshot, copying data from the new target to a clean target volume, and then deleting the corrupted snapshot. This segmentation allows independent restoration without requiring the original source disk to be accessible throughout the entire process.
Solution Approach 2:
The patent introduces an intermediary step by first creating a new target volume from the corrupted snapshot before performing the actual restoration. This intermediary new target volume serves as a bridge to restore data to a clean target volume, enabling restoration independence from the source disk.
2Reliability
If a clone is used to create an independent point-in-time copy, then the target disk is independent of the source disk, but storage space is consumed and the cleaning process becomes complex in cascaded configurations
Solution Approach 1:
The patent extracts the cleaning operation from the restoration process by performing it automatically during the restoration itself. The system identifies and removes the corrupted snapshot volume after successful restoration, eliminating the need for separate manual cleaning operations in cascaded configurations.
Solution Approach 2:
The restoration process is made self-service by automatically detecting corruption, creating a replacement target volume, performing the restoration, and deleting the corrupted snapshot without requiring manual intervention or complex external cleaning processes.
3Reliability
If metadata is used to track point-in-time copies in cascaded configurations, then data integrity is maintained, but metadata usage increases and storage efficiency decreases
Solution Approach 1:
The patent applies partial action by only creating and managing metadata for the new target volume during restoration, rather than maintaining extensive metadata for all possible cascade configurations. The system uses selective metadata tracking to maintain data integrity only where needed during the restoration process.
Data Source
AI summary
Managing storage volumes in a point-in-time copy cascade. The cascade includes a first source volume, a first point-in-time target volume, and a second point-in-time target volume. The second point-in-time target volume is a point-in-time copy of the first point-in-time target volume. Upon detecting a corruption of the first point-in-time target volume the method creates a third point-in-time target volume from the second point-in-time target volume and directs I/O operations for the first point-in-time target volume to the third point-in-time target volume. The first point-in-time target volume is restored to the second point-in-time target volume and, when the restoration is complete, deletes the first point-in-time target volume.