Transparent File System Migration via Inode Segmentation
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Solution Overview
Problem
Existing file system migration techniques face challenges in consolidating multiple source file systems into a single destination system without the need for a large and complex inode number mapping table, especially when source files can have the same inode numbers, leading to fragmentation and increased overhead.
Innovation Solution
The proposed solution involves splitting the inode number spaces into segments and using a deterministic mapping mechanism to allocate unique destination inode numbers, allowing for efficient consolidation of multiple source file systems into a single destination system, either in series or parallel, without the need for a per-inode mapping table.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large inode number mapping table is used to consolidate multiple source file systems into a single destination system, then all source files can be mapped to unique destination inode numbers, but the device complexity and overhead increase significantly
Solution Approach 1:
The patent divides the inode number space into multiple segments, where each segment can independently map inode numbers from different source file systems to the destination file system. This segmentation eliminates the need for a single large mapping table, reducing complexity while maintaining unique mapping capability across all source files.
2Productivity
If multiple source file systems are consolidated into a single destination system, then storage efficiency improves, but inode number fragmentation increases
Solution Approach 1:
By segmenting the inode number space into distinct ranges allocated to different source file systems, the patent prevents fragmentation. Each source file system's inode numbers are mapped to a dedicated segment in the destination, ensuring orderly allocation and eliminating the intermingling that causes fragmentation.
Solution Approach 2:
The patent applies different inode number segment allocations to different source file systems based on their specific needs and characteristics. Each source file system receives an appropriate inode number segment that matches its size and growth requirements, optimizing local resource allocation while maintaining global consolidation efficiency.
3Measurement precision
If a per-inode mapping table is used for each source file system, then precise tracking is achieved, but the overhead and memory consumption increase
Solution Approach 1:
The patent merges the tracking mechanism by using a single segmented inode number space at the destination file system that inherently tracks all source files. Instead of maintaining separate mapping tables for each source file system, the segmented destination inode space provides unified tracking with reduced memory overhead.
Data Source
AI summary
A system can migrate a source file system on a first computer to a destination file system on a second computer. The system can receive, at the second computer, a request from a client computer that indicates a file system operation, and that references a source file handle of the source file system that comprises an identifier of the source file system. The system can identify the destination file system based on the identifier of the source file system. The system can determine, from a source inode number of the source file handle, a source inode number segment. The system can determine, from the source inode number segment, a destination inode number segment. The system can determine, from the destination inode number segment, a destination inode number. The system can perform the file system operation on the destination file system using the destination inode number and the identifier of the destination file system.