Snapshot Checksum Trees for Incremental Consistency Validation
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Solution Overview
Problem
Existing data platforms struggle to determine the consistency of file system snapshots, as checksums do not indicate the correct order of chunks, leading to potential inconsistencies in snapshot validation, and recomputing checksums for entire snapshots is resource-intensive.
Innovation Solution
Incrementally generate aggregate checksums for portions of the snapshot by leveraging the data structure of the snapshot, computing checksums for modified chunks and avoiding recomputation for unmodified chunks, and storing these checksums to validate the snapshot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If checksums are computed for each chunk individually, then chunk validation is enabled, but snapshot consistency cannot be determined
Solution Approach 1:
The patent combines individual chunk checksums with their position information to create a snapshot-level aggregate checksum. This merging process allows the system to validate both individual chunks and the overall snapshot consistency simultaneously, resolving the contradiction between chunk-level validation and snapshot-level consistency checking.
Solution Approach 2:
The patent pre-computes and stores checksums for individual chunks during the snapshot creation process. This preliminary action enables efficient validation later without requiring re-computation, while also allowing the system to build aggregate checksums that capture ordering information for snapshot consistency verification.
2Reliability
If checksums are computed for the entire snapshot, then snapshot consistency is verified, but computing resources and time are excessively consumed
Solution Approach 1:
The patent segments the snapshot validation process into two levels: individual chunk checksum validation and aggregate snapshot checksum validation. By dividing the computation into manageable segments (individual chunks) and combining them systematically, the system achieves snapshot consistency verification with significantly reduced computational overhead compared to computing a single checksum over the entire snapshot.
Solution Approach 2:
The patent implements partial validation by allowing the system to verify snapshot consistency through aggregate checksums without necessarily validating every single chunk in detail. This partial action approach provides sufficient confidence in snapshot integrity while avoiding the excessive computational resources that would be required for complete exhaustive validation.
3Productivity
If checksums are recomputed for modified chunks in subsequent snapshots, then incremental updates are enabled, but the complexity of tracking modifications increases
Solution Approach 1:
The patent implements a feedback mechanism where the system compares aggregate checksums between consecutive snapshots to identify modifications. When the aggregate checksum changes, the system knows that some chunks have been modified and can trigger targeted re-computation. This feedback loop enables efficient incremental updates without requiring complex tracking of every individual chunk modification.
Solution Approach 2:
The patent uses checksum values as parameters to detect and track modifications. By monitoring changes in checksum parameters between snapshots, the system can efficiently identify modified chunks and trigger selective re-computation, avoiding the need for complex modification tracking mechanisms while maintaining high update efficiency.
Data Source
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AI summary
Techniques are described for incrementally determining checksums for a snapshot. An example method comprises identifying, by a data platform implemented by a computing system, a plurality of leaf nodes and a plurality of intermediate nodes in tree data corresponding to a snapshot of a storage system at a particular time, wherein the intermediate nodes each comprise one or more pointers identifying one or more of the leaf nodes, and the leaf nodes each include an indication of file system data of the storage system. The method includes determining, by the data platform, a checksum for each of the leaf nodes, determining, by the data platform, a checksum for each intermediate node based on the checksum of the one or more leaf nodes identified by the pointers of the intermediate node; and storing, by the data platform, the checksum for each of the leaf nodes and each of the intermediate nodes.