Snapshot Storage Space Reduction via Block Consolidation
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Solution Overview
Problem
Current storage systems face challenges in efficiently managing snapshot storage space, leading to insufficient storage and high management complexity, and are limited by the need for using the same type of hard disk drives for both source and snapshot volumes, which affects cost and performance.
Innovation Solution
A storage virtualization system that uses a Serial Attached SCSI (SAS) I/O device interconnect controller to manage snapshot images, allowing the use of different types of hard disk drives (SAS and SATA) with a single interface, and implements a section allocation system for flexible media management, including point-in-time backups and a purge mechanism to optimize storage space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple snapshot images are stored to capture data at different moments, then data security and fault tolerance are improved, but storage space consumption increases significantly and management complexity increases
Solution Approach 1:
The patent merges multiple snapshot images by identifying and consolidating common data blocks across snapshots. Instead of storing duplicate data blocks in each snapshot image, the system stores them once and creates references to shared blocks, significantly reducing storage space while maintaining data security and integrity.
Solution Approach 2:
The patent creates a universal storage structure where a single storage space serves multiple snapshot images simultaneously. The common data blocks are stored once and universally referenced by multiple snapshots, allowing the same physical storage to support multiple point-in-time backups without proportional space increases.
2Reliability
If multiple snapshot images are stored to capture data at different moments, then data security and fault tolerance are improved, but management complexity increases
Solution Approach 1:
The patent segments the snapshot management into distinct components: common data blocks, unique data blocks, and reference relationships. This segmentation allows independent management of each component through automated algorithms, reducing overall management complexity while maintaining comprehensive data security across all snapshots.
Solution Approach 2:
The patent implements self-service mechanisms where the system automatically identifies common data blocks, creates references, and manages snapshot consolidation without manual intervention. Automated algorithms handle the complex tasks of comparing snapshots, identifying duplicates, and maintaining reference integrity, significantly reducing management burden.
3Reliability
If copy-on-write procedure is performed for each snapshot image individually, then data integrity is maintained, but processing time increases
Solution Approach 1:
The patent performs preliminary identification of common data blocks across snapshot images before executing copy-on-write operations. By pre-analyzing and marking shared blocks, the system avoids redundant copy-on-write operations for identical data, maintaining data integrity while significantly reducing processing time.
Solution Approach 2:
The patent uses reference copying instead of physical data copying for common blocks. Instead of performing copy-on-write on duplicate data blocks, the system creates reference pointers to the single stored instance, maintaining data integrity through reference management while eliminating redundant copying operations.
Data Source
Figure 1A~1C
Figure 2~3
Figure 4A~4B
AI summary
This specification discloses a method of managing data snapshot images in a storage system. The method includes the steps of: establishing a section allocation system that includes at least a media extent; establishing a section allocation table and a block association set in the media extent, wherein the section allocation table has a field containing information pointing to the block association set and the block association set corresponds to a Source Volume as the basis for performing a snapshot backup thereof; establishing a block association table in the block association set, wherein the block association table is used to store cross-reference information in order to correspond to backup data with the original storage addresses; and copying the data before updating the data into the section association set, when the data in the Source-Volume need to be updated.