Layer-Based File Access for Virtualization Instances
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Solution Overview
Problem
In a library operating system (LibOS) environment, multiple instances waste storage space due to duplication of identical files, as each instance manages its own files without sharing.
Innovation Solution
A layer-based file access method is introduced, where a library operating system engine obtains an image file with multiple image subfiles, specifies these as layers, and uses a union file system to mount these subfiles into directories, creating a unified directory accessible by all instances, allowing access through a hypervisor that switches modes to facilitate host OS access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If each library operating system instance manages its own files independently, then file access simplicity is improved, but storage space is wasted due to file duplication across instances
Solution Approach 1:
The patent merges file management across multiple library operating system instances by implementing a shared file system where files are stored once and accessed by all instances. The file manager consolidates file operations into a unified namespace, allowing instances to share read-only files from a common storage location rather than maintaining separate copies, thereby reducing storage waste while maintaining access simplicity through the unified interface
Solution Approach 2:
The file manager is designed with universal functionality to serve multiple library operating system instances simultaneously. It provides a multi-functional interface that handles file operations for any instance through a common file system, enabling the same file storage infrastructure to be universally accessed by different instances without requiring instance-specific file management logic
2Loss of substance
If a shared file system is implemented across multiple instances, then storage space is saved by eliminating file duplication, but system complexity increases due to mode switching and hypervisor involvement
Solution Approach 1:
The patent introduces a file manager as an intermediary layer between library operating system instances and the underlying file system. This mediator handles all file operations, translating instance requests into standardized file system calls and managing the complexity of shared access, mode switching, and hypervisor interactions centrally, thereby isolating complexity from individual instances while enabling storage savings
3Adaptability or versatility
If instances access shared files through mode switching via hypervisor, then file sharing capability is improved, but access speed decreases due to mode transition overhead
Solution Approach 1:
The patent implements preliminary actions by pre-loading shared files into a unified file system namespace and caching frequently accessed files in memory before they are needed by multiple instances. The file manager pre-establishes file handles and access paths, so when instances need to access shared files, the data is already prepared and available, reducing the overhead of mode switching and improving access speed while maintaining sharing capability
Data Source
AI summary
The present disclosure discloses a file access method of a virtualization instance, including performing union on some image subfiles in a host operating system (host OS) and mounting a united directory to a union directory, and when an application in a library operating system instance needs to access a file in the union directory, causing a central processing unit to generate an exit event such that a hypervisor captures and processes the exit event, and during processing, converts an access request that is from the instance into an access request based on a system call of the host OS, and performs access.