Shadow Copy File Exclusion in Block-Based Backup
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Solution Overview
Problem
In block-based backups, it is challenging to exclude specific files and their metadata from the backup data, particularly in incremental backups, as the process requires identifying and omitting modified blocks associated with these files across volumes.
Innovation Solution
The solution involves creating a shadow copy of the source volume using the VSS (Virtual Shadow Copy Service) and employing a write tracker filter driver to track modifications, allowing for the exclusion of files by deleting them from the shadow copy volume and updating metadata, which helps in identifying blocks to be excluded from subsequent incremental backups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If block-based backup is performed at volume level, then backup efficiency is improved, but it becomes difficult to exclude specific files and their metadata from backup data
Solution Approach 1:
The patent segments the volume into individual file-level units by creating a shadow copy volume and deleting specific files from it. This allows the backup system to work with file-level granularity within the block-based backup framework, enabling selective exclusion of files while maintaining the efficiency of block-based backup for the remaining data.
Solution Approach 2:
The shadow copy volume acts as an intermediary between the source volume and the backup destination. By deleting files from the shadow copy rather than the source volume, the system enables file-level exclusion control without affecting the original data or requiring full file-by-file backup processing, thus resolving the contradiction between backup efficiency and file exclusion capability.
2Quantity of substance
If files are excluded from incremental backup, then storage space is saved, but it becomes necessary to track which modified blocks are associated with excluded files
Solution Approach 1:
The patent creates a shadow copy of the volume and performs file deletions on this copy rather than the source volume. The write tracker then monitors block changes in the shadow copy, automatically identifying blocks associated with deleted (excluded) files. This copying approach simplifies block tracking because the system only needs to monitor the shadow copy's block changes, not analyze file metadata across the entire file system.
Solution Approach 2:
The shadow copy volume and write tracker combination provides self-service block tracking. When files are deleted from the shadow copy, the write tracker automatically identifies the affected blocks through its monitoring of shadow copy modifications. This eliminates the need for complex external file system analysis to determine which blocks belong to excluded files, reducing tracking complexity while enabling storage space savings.
Data Source
AI summary
Techniques to back up data are disclosed. In various embodiments, a shadow copy of a source volume is created. An excluded file is deleted from the shadow copy. One or more blocks modified in the shadow copy in connection with deleting the excluded file from the shadow copy are tracked.