Multiple Protection Snapshot Copy System for Data Integrity
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Solution Overview
Problem
Existing snapshot technologies do not effectively protect against physical corruption of data, as they either incur significant overhead or introduce complexity when attempting to provide a point-in-time copy that is also resilient to hardware failures.
Innovation Solution
A multiple protection snapshot copy system that creates a snapshot by copying data to a first alternative storage area before writing and then pointing to a second area, allowing access to the logical device while ensuring data is also copied to the second area for redundancy, thus protecting against physical corruption with minimal overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full copy of the logical volume is performed to protect against physical corruption, then data protection reliability is improved, but the overhead and time required for snapshot creation increases significantly
Solution Approach 1:
The patent segments the copy operation into two distinct phases: a rapid pointer-based snapshot creation phase that provides immediate data protection, and a subsequent background copy phase that transfers data to alternative storage areas. This segmentation allows the snapshot to be created quickly without waiting for the full data copy, thus reducing snapshot creation time while maintaining data protection reliability through the eventual completion of the background copy.
Solution Approach 2:
The patent performs preliminary actions by creating the snapshot copy with pointer structures before the actual data copy is completed. The snapshot copy is initially created with pointers that will later be updated to point to data in alternative storage areas. This preliminary snapshot creation provides immediate data protection capability without requiring the time-consuming full data copy to be completed first.
2Reliability
If a full copy is performed to protect against physical corruption, then data protection reliability is improved, but device complexity increases due to additional coordination requirements
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of pointer structures that mediate between the snapshot copy and the alternative storage areas. These pointers serve as intermediaries that simplify the coordination required for full copy operations, allowing the snapshot to reference data in alternative storage without requiring complex real-time synchronization or coordination protocols during the copy process.
Solution Approach 2:
The patent uses a simplified copy approach where the snapshot copy contains pointer structures that reference data locations. Instead of implementing complex real-time data synchronization mechanisms, the system uses straightforward pointer updates to redirect references from the snapshot to alternative storage areas, reducing the complexity of coordination required for data protection.
3Productivity
If a snapshot copy is created with pointers to logical volume sections, then snapshot creation overhead is reduced, but protection against physical corruption is lost
Solution Approach 1:
The patent performs preliminary snapshot creation with pointer structures to achieve rapid snapshot deployment, then subsequently updates the pointers to reference data in alternative storage areas. This two-stage approach maintains productivity during the initial snapshot creation while ensuring reliability through the follow-up pointer update that redirects references to protected data locations.
Solution Approach 2:
The patent segments the snapshot creation and data protection functions into distinct phases: the snapshot copy structure is created quickly with initial pointers, and then the data protection is established through a separate background process that updates pointers to reference alternative storage areas. This segmentation maintains high productivity for snapshot creation while ensuring reliability through the subsequent protection phase.
Data Source
AI summary
Providing a multiple protection snapshot copy of a logical device includes creating the snapshot copy of the logical device, where, in response to a write to a section of the logical device, data is copied to a first alternative storage area prior to the write and, following creating the snapshot copy, pointing portions of the snapshot copy to a second alternative storage area having data that is a copy of the logical device, where data corresponding to the snapshot copy is stored in one of: the first alternative storage area and the second alternative storage area. Providing a multiple protection snapshot copy of a logical device may also include, prior to pointing portions of the snapshot copy to the second alternative storage area and after creating the snapshot copy, copying data from the logical device to the second alternative storage area.