Lun Clone Backup Space Optimization via Differential Transfer
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Solution Overview
Problem
Previous methods for backing up lun clones from a primary server to a secondary server fail to preserve the space-saving relationship between luns and lun clones, resulting in increased data storage space requirements and duplicate data on the secondary server.
Innovation Solution
The method involves transferring lun clones as lun clones, maintaining the space-saving relationship by creating snapshots of the backing luns and lun clones, and updating the secondary server to replicate this relationship, thereby reducing data storage space and transfer volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lun clones are backed up by copying all data blocks to the secondary server, then data consistency is ensured, but data storage space on the secondary server increases significantly and duplicate data is created
Solution Approach 1:
The backup process is segmented into two parts: (1) backing up the backing lun by transferring its snapshot, and (2) backing up the lun clone by transferring only its unique data blocks. This segmentation allows the system to maintain data consistency while avoiding duplication of shared data blocks between the backing lun and its clones.
Solution Approach 2:
The patent extracts only the unique data blocks from the lun clone that are not shared with the backing lun. By identifying and transferring only these differential blocks rather than all data blocks, the system reduces the quantity of data stored on the secondary server while maintaining the ability to reconstruct the complete lun clone state.
2Reliability
If all data blocks of lun clones are transferred to the secondary server, then complete backup is achieved, but network bandwidth usage increases
Solution Approach 1:
The system extracts and transfers only the differential data blocks that exist in the lun clone but not in the backing lun. This extraction approach ensures backup completeness for the clone-specific modifications while minimizing network bandwidth consumption by excluding redundant shared data blocks.
Solution Approach 2:
Instead of performing a complete copy of all data blocks, the system performs a partial action by transferring only the necessary differential blocks. This partial backup approach is sufficient to maintain backup completeness since the original backing lun serves as the base, and only the clone-specific changes need to be preserved.
3Reliability
If lun clones are restored by transferring all data blocks from the secondary server, then data recovery is ensured, but data transfer time increases
Solution Approach 1:
The restore process is segmented into two efficient steps: (1) restoring the backing lun from its snapshot on the secondary server, and (2) applying only the differential data blocks to recreate the lun clone. This segmentation dramatically reduces restore time compared to transferring all data blocks, while ensuring complete data recovery through the combination of base image and differential updates.
Solution Approach 2:
The backing lun snapshot is prepared and stored on the secondary server in advance as part of the backup process. During restoration, this pre-prepared snapshot serves as the foundation, allowing the system to quickly reconstruct lun clones by applying only the differential blocks without needing to transfer or process the entire data set again.
Data Source
AI summary
Lun clones are transferred from a primary server to a secondary server. The lun clones on the secondary server maintain the same data storage space saving relationship with backing luns of the lun clones as exists on the primary server. Incremental backups and restores of the lun clones between the primary and secondary servers involves transferring less than the total number of data blocks associated with the lun clone.