Virtual ISO Image Metadata Extraction for VM Storage Efficiency
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Solution Overview
Problem
Creating and maintaining ISO images for virtual machines is time-consuming and storage-intensive, especially when new file versions become available, as existing methods require copying large amounts of data and duplicating files.
Innovation Solution
A virtual ISO image is created that stores only metadata for an ISO 9660 file system, with start offsets and sizes of application data files, allowing a custom I/O handler to service read requests by mapping sector offsets to actual file data locations, reducing the need for copying file data and enabling efficient access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete ISO images are created and maintained for virtual machines, then access to file systems is enabled, but storage space consumption and creation time increase significantly
Solution Approach 1:
The patent extracts only the essential metadata (directory records, volume descriptors) from the complete ISO image, storing these in a compact virtual image file while the actual file data remains in its original location. This separation allows the virtual machine to access the file system structure without duplicating the entire ISO image, dramatically reducing storage requirements while maintaining full file system functionality.
Solution Approach 2:
The patent introduces a custom I/O handler as an intermediary component that sits between the virtual machine and the scattered file data. This handler intercepts read requests, translates virtual device sector offsets to actual file positions using the stored metadata, and retrieves data on-demand. This mediation enables complete file system access without requiring the complete ISO image to be present locally.
2Reliability
If complete ISO images are created and maintained for virtual machines, then access to file systems is enabled, but creation time increases significantly
Solution Approach 1:
The patent extracts only the essential metadata (directory records, volume descriptors) from the complete ISO image, storing these in a compact virtual image file while the actual file data remains in its original location. This separation allows the virtual machine to access the file system structure without duplicating the entire ISO image, dramatically reducing storage requirements while maintaining full file system functionality.
Solution Approach 2:
The system performs preliminary extraction of only the necessary metadata (directory structure, volume descriptors) when creating the virtual image, rather than copying the entire ISO image. This preliminary action creates a lightweight placeholder that can be generated quickly, while the actual file data is accessed on-demand from its original location during runtime.
3Adaptability or versatility
If new file versions are written to existing ISO images, then updated content is available, but the process requires recreating complete ISO images which is time-consuming
Solution Approach 1:
The patent implements a dynamic system where the virtual image metadata can be updated in-place without recreating the entire ISO image. When files are added, modified, or deleted, only the relevant metadata structures (directory records, volume descriptors) are updated, and the changes are immediately reflected in subsequent virtual machine accesses. This dynamic update capability eliminates the need for time-consuming complete image recreation.
Solution Approach 2:
The system allows individual files to be discarded (deleted) or recovered (added/modified) independently without affecting the overall image structure. When a file changes, only that specific file's data and its corresponding metadata entries are updated, while the rest of the virtual image structure remains intact and reusable.
4Quantity of substance
If metadata is stored apart from file system data, then storage efficiency improves, but data location determination complexity increases
Solution Approach 1:
The patent introduces a custom I/O handler as an intermediary component that sits between the virtual machine and the scattered file data. This handler intercepts read requests, translates virtual device sector offsets to actual file positions using the stored metadata, and retrieves data on-demand. This mediation enables complete file system access without requiring the complete ISO image to be present locally.
Data Source
AI summary
One embodiment of the present invention is a method for a virtual machine to access data from a virtual device, the method including: (a) attaching the virtual device to the virtual machine with a backing store that is a virtual image of a file system conforming to a predetermined file system format, wherein: (i) file system data is stored in one or more files, (ii) the virtual image includes metadata stored apart from the file system data, which metadata corresponds to the predetermined file system format, (iii) the metadata includes one or more directory records, and (iv) the one or more directory records include information that points directly or indirectly to the file system data; (b) issuing a read request for a block of data from the file system as if stored in the predetermined file system format; (c) accessing the metadata and determining the location of the requested block of data in the file system data; and (d) retrieving the requested block of data from the file system data.