Mapper Tree Super Leaf Nodes Sparse Write Metadata
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Solution Overview
Problem
Existing data storage systems require a disproportionately large amount of metadata to support logical volumes, especially when writes are sparsely distributed across the logical address space, leading to inefficient resource utilization.
Innovation Solution
The introduction of super leaf nodes in a mapper tree, where multiple leaf nodes are efficiently represented within a single super leaf node, reducing the need for new nodes in the leaf level and optimizing metadata storage by adding new leaf nodes to super leaf nodes instead of creating separate nodes in the leaf level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual leaf nodes are added to the mapper tree for each segment of logical address space, then the mapping accuracy is improved, but the amount of metadata increases disproportionately
Solution Approach 1:
The patent merges multiple leaf nodes that correspond to different segments of logical address space into a single shared leaf node. Instead of creating separate leaf nodes for each sparse write location, the system combines them and uses a single node to store mappings for multiple segments, thereby reducing metadata while maintaining mapping accuracy.
Solution Approach 2:
The shared leaf node serves multiple functions by storing mappings for multiple segments of logical address space simultaneously. This multi-functional node replaces what would traditionally require multiple separate leaf nodes, reducing the overall metadata quantity while preserving the ability to accurately map any segment within the logical volume.
2Productivity
If the mapper tree is optimized for sparse writes, then storage efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent segments the logical address space into multiple segments that can be mapped to different portions of physical storage. By organizing the mapper tree to handle segments collectively through shared leaf nodes, the system achieves efficient sparse write handling without requiring complex individual node structures for each segment.
Solution Approach 2:
The shared leaf node acts as an intermediary structure that mediates between multiple segments of logical address space and the physical storage pages. This intermediary approach simplifies the overall tree structure compared to having direct individual mappings, while still enabling efficient sparse write operations.
Data Source
AI summary
A mapper tree for a logical volume is provided by storing, in each leaf node of the mapper tree, pointers to pages of non-volatile storage that store host data written to corresponding pages within a segment of the logical address space of the logical volume that corresponds to the leaf node. In response to receiving an initial write operation directed to a segment of the logical address space of the logical volume for which no leaf node currently exists in the mapper tree, a representation of a new leaf node is added to a super leaf node in the mapper tree that efficiently stores representations of multiple leaf nodes.