Point-in-time Backup Images Reducing Copy-on-Write Overhead
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Solution Overview
Problem
Current backup techniques face challenges in providing point-in-time consistent backup images due to significant computing overhead caused by copy-on-write operations, leading to inconsistent data blocks and overburdened systems during large or frequent writes.
Innovation Solution
A method and apparatus that process inconsistent data blocks by updating backup images using snapshot images created after the backup process, utilizing bitmap information to identify and correct inconsistencies, thereby reducing the number of copy-on-write operations and ensuring point-in-time consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If snapshot based backup techniques are used to provide point-in-time consistent backup images, then backup consistency is improved, but computing overhead increases due to copy-on-write operations
Solution Approach 1:
The patent creates a snapshot image after the backup process completes, rather than during the backup process. This preliminary action (creating snapshot after backup) allows the system to capture the final state without interfering with the backup operations, thereby avoiding copy-on-write overhead during backup while still providing point-in-time consistency for recovery purposes
Solution Approach 2:
The patent creates a copy (snapshot image) of the data blocks after backup to preserve the post-backup state. This copying approach allows the system to maintain backup consistency without requiring copy-on-write operations during the backup process itself, thus reducing computing overhead while ensuring reliability
2Loss of information
If frequent writes occur on the original volume during backup, then data freshness is improved, but the number of copy-on-write operations increases
Solution Approach 1:
By creating the snapshot image after the backup process completes rather than during it, the system allows frequent writes to occur on the original volume without triggering copy-on-write operations. The snapshot captures the final state after all writes are complete, maintaining data freshness information while preserving backup process efficiency
Solution Approach 2:
The patent extracts the snapshot creation operation from the backup process timeline, placing it after backup completion. This separation allows the backup process to proceed efficiently without being burdened by copy-on-write operations, while the extracted snapshot creation step captures the final data state for consistency purposes
3Reliability
If a full backup process is performed on a volume, then complete data coverage is improved, but backup window size increases
Solution Approach 1:
The patent performs the snapshot creation as a preliminary action after backup completion rather than as part of the backup process. This allows the full backup to complete its data coverage mission without the time penalty of concurrent snapshot operations, reducing the effective backup window while maintaining complete data coverage
Solution Approach 2:
The system uses periodic full backups combined with post-backup snapshot creation. This periodic approach ensures complete data coverage at regular intervals while minimizing the impact on backup windows by separating the snapshot creation from the backup execution time
Data Source
AI summary
A method and apparatus for providing point-in-time consistent backup images while reducing a computing overhead associated with copy-on-write operations for snapshot images is described. In one embodiment, the method comprises processing at least one data block that is inconsistent with a backup image; and updating the backup image with the at least one inconsistent data block from a snapshot image, wherein the snapshot image is created after a backup process, wherein the updated backup image is point in time consistent.