B+Tree Snapshot Metadata Verification via Breadth-First Traversal
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Solution Overview
Problem
Traditional methods for verifying metadata consistency in snapshot hierarchies using copy-on-write B+ trees are inefficient, requiring redundant traversals and resource duplication, which can lead to performance issues and inconsistencies.
Innovation Solution
Implementing a breadth-first traversal approach combined with in-memory node maps and global node maps to ensure each snapshot's B+ tree logical map is traversed and verified only once, reducing redundant efforts and resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional depth-first traversal methods are used to verify snapshot metadata, then verification can be performed, but redundant traversals and resource duplication occur leading to performance degradation
Solution Approach 1:
The patent applies preliminary action by performing a breadth-first traversal to identify all ancestor snapshots before verifying the child snapshot. This allows the system to pre-load ancestor metadata into memory and create a verification map, avoiding redundant traversals during the actual verification process. The verification map is prepared in advance to quickly check node sequence number consistency across snapshots.
Solution Approach 2:
The patent uses copying by creating a verification map that contains metadata from ancestor snapshots in memory. Instead of repeatedly accessing and traversing the actual snapshot metadata structures multiple times, the system copies the necessary ancestor metadata into this verification map, which can be quickly queried during verification without causing redundant I/O operations or memory allocations.
2Reliability
If redundant metadata traversals are performed for each snapshot, then verification coverage is ensured, but computational resources and time are wasted
Solution Approach 1:
The patent merges the verification process by performing a single breadth-first traversal that simultaneously identifies all ancestor snapshots and collects their metadata. This combined approach ensures that all necessary verification data is gathered in one pass, eliminating the need for separate traversals for each snapshot and reducing total verification time while maintaining complete verification coverage.
Solution Approach 2:
The system performs preliminary action by pre-loading all ancestor snapshot metadata into memory during the breadth-first traversal phase. This preliminary data collection allows subsequent verification operations to proceed without additional traversals, as all necessary metadata is already available in the verification map for immediate comparison and validation.
3Reliability
If comprehensive snapshot verification is performed, then metadata inconsistencies are detected, but system resources are excessively consumed
Solution Approach 1:
The patent extracts only the necessary metadata from ancestor snapshots into the verification map during the breadth-first traversal. Instead of copying or processing entire snapshot structures, the system extracts specifically the node sequence numbers and metadata identifiers needed for verification. This selective extraction reduces memory consumption and computational overhead while maintaining the ability to detect all metadata inconsistencies.
Data Source
AI summary
A method for verifying a consistency of snapshot metadata maintained in an ordered data structure for a plurality of snapshots in a snapshot hierarchy is provided. The method includes identifying a first plurality of nodes maintained in a first ordered data structure for a first snapshot that is a child of a second snapshot; for a first node of the first plurality of nodes, verifying the first node by checking for the first node in a second node map maintained in memory for the second snapshot, wherein the second node map includes a plurality of verified nodes in a second ordered data structure; and based on whether the first node is in the second node map: adding the first node to a first node map maintained in memory for the first snapshot, wherein the first node map includes verified nodes of the first plurality of nodes; or triggering an alarm.