File-Level Backup Tracking Using Volume CBT After Reboots
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Solution Overview
Problem
Existing file system changed block tracking (FS CBT) methods face reliability issues during server reboots, leading to inefficient use of computing resources due to the inability to accurately track file level changes when the file system is detached, resulting in full volume scans and resource consumption.
Innovation Solution
Leveraging volume level CBT to track changes reliably by interfacing with the file system to identify file mapping information, allowing for more accurate FS CBT even during reboots, thereby reducing the need for full volume scans and conserving computing resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FS CBT is performed to enable file level backup, then backup efficiency is improved, but reliability deteriorates during reboots when file system detaches
Solution Approach 1:
The patent introduces volume level CBT as an intermediary mechanism between the file system and backup agent. When FS CBT cannot be performed (e.g., during reboots), the volume level CBT serves as a fallback to track changed blocks at the volume level, ensuring continuous backup capability without complete loss of change tracking functionality.
Solution Approach 2:
The system performs preliminary actions by maintaining volume level CBT information in advance. This volume level CBT data is prepared and stored before file system detachment occurs, so when FS CBT becomes unavailable during reboots, the pre-prepared volume level information can be used to reconstruct file level change tracking after recovery.
2Reliability
If full volume scan is performed after reboot to determine file changes, then reliability of change detection is improved, but computing resource consumption increases
Solution Approach 1:
The patent extracts the essential change tracking information from the full volume scan by using volume level CBT data. Instead of scanning the entire volume to detect changes, the system extracts only the changed block information from volume level CBT and intersects it with file mapping information, significantly reducing computing resources while maintaining reliable change detection.
Solution Approach 2:
Rather than performing a complete full volume scan (excessive action), the system performs partial scanning by leveraging volume level CBT to identify only the subset of blocks that have changed. This partial action approach maintains reliability of change detection while minimizing computing resource consumption during post-reboot operations.
3Measurement precision
If file system CBT is implemented for file level backup, then backup precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the change tracking functionality into two distinct levels: FS CBT for file level precision and volume level CBT for reliable block tracking. This segmentation allows the system to use the simpler volume level CBT as a foundation and overlay file level precision only when needed, reducing overall complexity while maintaining high precision capability.
Solution Approach 2:
The volume level CBT mechanism serves multiple functions: it acts as the primary change tracking method during normal operations and as a fallback mechanism during reboots when FS CBT is unavailable. This multi-functionality reduces the need for separate complex mechanisms for each scenario, simplifying the overall system architecture while maintaining file level backup precision.
Data Source
AI summary
A computing device comprising a storage device and processing circuitry may perform the techniques of this disclosure. The storage device may have a plurality of blocks forming a volume. The processing circuitry may obtain volume changed block tracking (CBT) information identifying one or more of the blocks storing updated data that has changed relative to a previous backup of the one or more blocks, and determine file mapping information identifying one or more blocks of the plurality of blocks that store file data associated with a file. The processing circuitry may also determine, based on the volume CBT information and the file mapping information, file system CBT information identifying whether at least one of the one or more blocks store file data associated with the file have changed, and initiate, based on the file system CBT information, a subsequent backup of at least a portion of the file data.