Point-in-time Copy Restore Cascade Management
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Solution Overview
Problem
Existing point-in-time copy solutions in computer storage systems face challenges with cascaded implementations, where multiple target point-in-time copies introduce dependencies that lead to inefficient cleaning processes and storage allocation issues, particularly when using space-efficient volumes, resulting in prolonged backup times and potential storage inefficiencies.
Innovation Solution
A method is introduced that manages storage volumes in a point-in-time copy cascade by detecting corruption and creating a new target volume to redirect I/O operations, allowing for independent restoration of the source volume, thereby reducing dependencies and optimizing storage usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If snapshot copies are cascaded together to represent the primary disk at various times, then storage space is reduced through thin provisioning, but the target disk remains dependent on the source disk to reassemble a complete copy
Solution Approach 1:
The patent segments the restoration process by creating an intermediate target volume that receives data from the source disk independently of the snapshot cascade. This intermediate volume then serves as the source for restoring other volumes in the cascade, breaking the chain of dependencies and allowing parallel restoration operations.
Solution Approach 2:
The patent introduces an intermediate target volume as a mediator in the restoration process. This intermediate volume receives data directly from the corrupted source disk and then supplies data to other target volumes, eliminating the need for those volumes to depend on each other for restoration.
2Adaptability or versatility
If a second restoration is required during the first restoration, then access to the second restoration can be delayed due to dependency chains
Solution Approach 1:
The patent segments the restoration operations into independent parallel processes by using intermediate target volumes. Each restoration operation can proceed independently without waiting for other restorations to complete, enabling simultaneous execution of multiple restoration tasks.
Solution Approach 2:
The patent performs preliminary action by creating intermediate target volumes that contain complete data copies before restoration is needed. These pre-prepared intermediate volumes serve as immediate sources for restoration operations, eliminating delays that would occur if data had to be assembled from snapshot dependencies during restoration.
3Reliability
If clone is created by executing background copy procedure followed by copy-on-write procedure, then complete copy is achieved with independence from primary disk, but storage space consumption increases
Solution Approach 1:
The patent segments the copy independence requirement into selective application. Instead of making all target volumes completely independent like clones, it creates independence only where needed through intermediate target volumes, while allowing snapshot volumes to remain dependent and space-efficient.
Solution Approach 2:
The patent applies different copy independence qualities to different parts of the system. Intermediate target volumes have complete independence (clone-like), while snapshot target volumes maintain dependency (snapshot-like). This local differentiation allows the system to achieve necessary reliability without universally increasing storage consumption.
Data Source
AI summary
Managing storage volumes in a point-in-time copy cascade. The cascade includes a first source volume, a first target volume and a second target volume. The method detects a corruption of the first source volume and, if a first restoration of the first source volume from the first target volume is in progress, creates a third target volume from the second target volume and directs I/O operations for the first source volume to the third target volume. The first source volume is then restored from the third target volume.