Bitmap-Based File Virtualization for Large Sandboxed Files
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Solution Overview
Problem
Existing file virtualization methods for large files in sandboxes are inefficient as they require copying the entire file upon modification, leading to time-consuming operations and wasteful disk storage usage.
Innovation Solution
The method divides large files into clusters and uses a bitmap to track modifications, allowing only changed parts to be redirected to a shadow file, eliminating unnecessary data duplication and reducing disk storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire file is copied to shadow file upon modification, then file virtualization is achieved, but time consumption and disk storage are significantly increased
Solution Approach 1:
The patent divides large files into smaller clusters (e.g., 4KB each) and creates a bitmap where each bit represents whether a corresponding cluster has been modified. This segmentation allows the system to track and copy only modified clusters rather than entire files, dramatically reducing copy operation time while maintaining file virtualization functionality.
Solution Approach 2:
Instead of copying entire files unnecessarily, the patent implements partial copying by using the bitmap to identify only the specific clusters that have been modified. This partial action principle ensures that copy operations are performed only when and where needed, optimizing both time efficiency and storage utilization.
2Reliability
If the entire file is copied to shadow file upon modification, then file virtualization is achieved, but disk storage is wasted
Solution Approach 1:
The patent segments files into clusters and uses a bitmap to track modifications at the cluster level. This enables the system to store only modified clusters in the shadow file rather than duplicating entire files, significantly reducing disk storage consumption while preserving file virtualization capabilities.
Solution Approach 2:
The bitmap mechanism allows the system to identify and discard unnecessary data copies. By tracking which clusters have been modified, the system avoids storing redundant copies of unchanged data, effectively recovering disk storage space that would otherwise be wasted.
3Ease of operation
If a shadow file is created for every write operation, then file access redirection is achieved, but overall sandbox performance deteriorates
Solution Approach 1:
The patent divides files into clusters and uses a bitmap to track modifications, allowing the system to create and manage shadow files more efficiently. By operating at the cluster level rather than file level, the system reduces the overhead of shadow file creation and management, improving sandbox performance while maintaining file access redirection functionality.
Solution Approach 2:
The system performs partial copy operations only for modified clusters rather than entire files. This partial action approach significantly reduces the computational overhead and I/O operations required for shadow file management, thereby improving overall sandbox performance while preserving file access redirection.
Data Source
AI summary
There is provided a method and system with an improved bitmap access control method of file virtualization for large files in sandbox. The process divides a large file to pieces clusters by fixed byte counts, building a mapping relationship between logical view of sandboxed file and physical shadow file on disk. Thus, there is no need to copy an entire file when a file is modified and waste the user's disk storage.