File Level Recovery for Virtual Hard Disks
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Solution Overview
Problem
Current backup systems do not support file level restore processes for dynamic and virtual hard disks, as they fail to detect and recover files from VHD disks due to memory-mapped formats and cannot handle dynamic disks with the same UUID as iSCSI disks, leading to inefficient recovery processes.
Innovation Solution
Implementing a file level recovery process that uses a helper VM to detect and mount VHD and dynamic disks, enabling file level recovery by maintaining disk mappings and using handshaking mechanisms for mounting and unmounting simple disks, allowing for the detection and recovery of files across restore points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If file level recovery is implemented for VHD disks, then file recovery capability is improved, but detection reliability deteriorates because VHD disks are memory-mapped and mappings are lost when VM is powered
Solution Approach 1:
The system performs preliminary scanning and detection of VHD disks while the VM is still powered on and memory mappings are valid. It captures disk information, file structures, and metadata before the VM shutdown causes mapping loss, enabling subsequent file level recovery operations without requiring active memory mappings.
Solution Approach 2:
The system creates a copy or snapshot of the VHD disk structure and file system metadata while memory mappings are still valid. This copied information is stored in a persistent format that can be accessed later for file level recovery, eliminating the need for real-time memory mapping access.
2Adaptability or versatility
If file level restoration is implemented for dynamic disks with iSCSI, then file recovery capability is improved, but system compatibility deteriorates because iSCSI disks and original disks have the same UUID causing online failures
Solution Approach 1:
The system segments the disk identification process by separating the recovery disk from the original production disk. It creates distinct virtual disk representations with modified or unique identifiers in the recovery environment, preventing UUID conflicts while maintaining file level restoration capability for dynamic iSCSI disks.
Solution Approach 2:
The system introduces an intermediary layer or virtualization mechanism between the recovery files and the target disk. This intermediary handles the UUID mapping and identification, allowing file level restoration to proceed without direct UUID conflicts between iSCSI disks and original disks.
3Device complexity
If serial browsing through all backups is used to locate a particular backup file, then backup system simplicity is maintained, but recovery time increases significantly especially with daily backups creating multiple restore points
Solution Approach 1:
The system implements feedback mechanisms that provide users with searchable information about available backups, including timestamps, file contents, and metadata. This feedback enables users to quickly identify and locate specific restore points without manually browsing through all backups in serial order.
Solution Approach 2:
The system performs preliminary organization, indexing, and metadata generation for all backup files during the backup process. This preliminary action creates a searchable database of backup contents, enabling rapid location and retrieval of specific files or restore points without requiring sequential browsing of all backups.
Data Source
AI summary
Embodiments are described for enabling file level recovery (FLR) process for dynamic and VHD disks in a data storage system. For VHD disks, certain intelligence is provided to a FLR agent installed in a helper VM to discover the VHD disks in the source VM. The FLR agent detects the presence of the VHD disk in the source VM, and upon detection, performs an Instant Recover (IR) operation of the source VM. It mounts the VHD disk and contained VHD files in the source VM on the helper VM to expose the VHD files to the FLR operation, and a backup operation copies the exposed VHD files to a destination folder on a destination VM. The memory mapping to the VHD disk is maintained by the helper VM during the FLR operation.