Virtual Copy for Multi-Read Access of Exclusive Virtual Disks
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Solution Overview
Problem
Existing systems for virtualized backup image copies face inefficiencies due to exclusive single-session access, which prevents concurrent operations and lengthens backup processes by requiring serialized access and delaying catalog generation, thus hindering multi-session support and granular restore operations.
Innovation Solution
A backup system that generates virtual copies of backup images, allowing the hypervisor to lock the virtual copy instead of the original image, enabling the filter driver to route access requests between the backup image and virtual copy, thereby supporting multi-session access without compromising data consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exclusive single-session access is enforced on backup virtual disk files, then data consistency is protected, but multi-session support is prevented and backup operations are serialized
Solution Approach 1:
The patent creates a virtual copy of the backup virtual disk file, allowing the hypervisor to lock the copy instead of the original. This enables multiple sessions to access the original backup file simultaneously while the virtual copy maintains data consistency through exclusive locking.
Solution Approach 2:
The patent introduces a virtual file filter driver as an intermediary layer between the hypervisor and the backup virtual disk file. This driver intercepts I/O requests, redirects them to the virtual copy when locked, and manages the locking mechanism to enable multi-session access while preserving data integrity.
2Adaptability or versatility
If catalog generation is performed during backup operation, then granular restore capability is enabled, but backup time is significantly increased
Solution Approach 1:
The patent generates the catalog during the backup operation itself, but does so efficiently by leveraging the virtual copy mechanism. The catalog is built in advance before browse operations begin, eliminating the need to delay catalog generation and allowing immediate multi-session access without time loss.
3Reliability
If virtual disk file is locked by hypervisor, then protection against consistency problems is achieved, but concurrent operations are prevented
Solution Approach 1:
The patent creates a virtual copy of the backup virtual disk file, allowing the hypervisor to lock the copy instead of the original. This enables multiple sessions to access the original backup file simultaneously while the virtual copy maintains data consistency through exclusive locking.
Solution Approach 2:
The patent separates the locking function from the data storage function by creating a virtual copy. The original backup file remains unlocked and accessible to multiple sessions, while the virtual copy handles exclusive locking requirements, dividing the system into independent functional segments.
Data Source
AI summary
A system and method for efficient dynamic browsing of virtualized backup images. A client computer sends to a backup server a request to open a browse session for a given backup image stored on a backup medium which may be a virtual disk file. The virtual disk file is typically locked by a hypervisor for protection against consistency problems. A backup application creates a virtual copy for the given backup image if it doesn't already exist. The backup application directs each of a virtual file filter and the hypervisor to open the virtual copy in order to obtain information for later redirections and to create a lock file for the virtual copy. The backup application and the virtual file filter route access requests to the given backup image and the virtual copy based on the of access request.