Point-in-Time Snapshot Generation for Deduplication Volumes
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Solution Overview
Problem
Conventional data protection systems face challenges in efficiently generating and accessing point-in-time snapshots of deduplication-based volumes, particularly in replication systems, where data integrity and recovery are critical but performance and efficiency are compromised.
Innovation Solution
The method involves generating a virtual access data structure and modifying a preliminary snapshot to point to blocks according to this structure, enabling the creation of a point-in-time snapshot of deduplication-based volumes, which allows for efficient data access and recovery without redirecting I/Os through the data protection appliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional data protection systems use traditional snapshot methods for deduplication-based volumes, then data integrity is maintained, but snapshot generation speed and data access performance deteriorate
Solution Approach 1:
The snapshot generation process is segmented into two phases: (1) creating a preliminary snapshot by copying only metadata structures (bitmap, inode tables, directory structures) without actual data blocks, and (2) selectively redirecting I/O operations to appropriate locations. This segmentation allows rapid snapshot creation while maintaining data integrity through the virtualization layer.
Solution Approach 2:
A virtualization layer is introduced as an intermediary between the host and the deduplication storage array. This virtualization layer includes data structures (bitmap, inode tables, directory structures) that mediate I/O operations, redirecting reads to snapshot data blocks and writes to the production volume, thereby enabling fast snapshot access without compromising data integrity.
2Reliability
If I/O operations are redirected through the data protection appliance for snapshot access, then data consistency is maintained, but access performance and efficiency worsen
Solution Approach 1:
The system performs preliminary actions during snapshot creation by pre-establishing the virtualization layer with all necessary metadata structures (bitmap, inode tables, directory structures) and pre-identifying data block locations. This preliminary setup enables direct I/O access to snapshot data without requiring real-time redirection through the data protection appliance, thus improving access performance while maintaining consistency.
3Reliability
If traditional snapshot methods are used for deduplication volumes, then complete data copies are created ensuring reliability, but storage efficiency and access speed deteriorate
Solution Approach 1:
Instead of copying actual data blocks, the system creates a virtual copy by duplicating only the metadata structures (bitmap, inode tables, directory structures) that describe the data layout. The actual data blocks remain shared between the production volume and snapshot, referenced through the virtualization layer. This approach ensures data completeness while dramatically improving storage efficiency.
Data Source
AI summary
In one aspect, a method to generate a point-in-time (PIT) snapshot of deduplication-based volume includes generating a virtual access data structure, generating a preliminary snapshot of the volume and modifying the preliminary snapshot to point to a block according to the virtual access data structure to generate the PIT snapshot of the deduplication-based volume.