Delta Queue Data Protection Without Snapshot Stun
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Solution Overview
Problem
Existing backup technologies suffer from high recovery point objective (RPO) due to the performance impact caused by snapshot operations, which stun or quiesce computing systems, limiting the number of snapshots that can be performed, and require complex differential operations that are difficult to manage.
Innovation Solution
A one-pass delta mechanism using two bitmaps to track changes in virtual machine volumes, allowing near continuous data protection with reduced RPO to seconds, eliminating the need for a splitter and simplifying the generation of deltas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If snapshot operations are performed to protect data, then data protection capability is improved, but system performance deteriorates due to stunning or quiescing the computing system
Solution Approach 1:
The patent segments the data protection process into change tracking (using bitmaps to identify modified blocks) and selective copying (transferring only changed data). This segmentation allows continuous data protection without requiring system quiescence, as the tracking and copying operations can proceed independently of the running system's I/O operations.
Solution Approach 2:
The patent performs preliminary actions by maintaining change trackers (bitmaps) that continuously monitor and record data modifications before backup is needed. This preliminary tracking eliminates the need for snapshot operations at backup time, as the changes are already identified and can be copied immediately without system interruption.
2Reliability
If traditional snapshot methods are used to achieve data protection, then data protection is provided, but recovery point objective (RPO) increases due to limited number of snapshots that can be performed
Solution Approach 1:
The patent implements continuous data protection by continuously tracking data changes using bitmaps and continuously copying changed blocks to backup storage. This continuous operation eliminates the discrete, periodic nature of traditional snapshots, enabling near-zero RPO as changes are protected as they occur rather than at periodic intervals.
Solution Approach 2:
By preliminarily tracking all data changes in bitmaps before backup is required, the system prepares the information needed for immediate backup of only the changed data. This preliminary tracking enables the system to achieve low RPO without performing multiple snapshot operations, as the change information is already available when backup is initiated.
3Reliability
If snapshot operations are performed frequently to reduce RPO, then data protection frequency is improved, but system performance continues to deteriorate due to repeated stunning or quiescing
Solution Approach 1:
The patent segments the data protection function into two independent parts: change detection (using bitmaps that track modifications) and data transfer (copying changed blocks). This segmentation allows the change detection to occur continuously without system interruption, while data transfer can proceed at backup capacity without affecting production I/O performance.
Solution Approach 2:
The system performs preliminary change tracking using bitmaps that continuously monitor data modifications before backup is needed. This preliminary tracking eliminates the need for repeated snapshot operations, as the change information is already captured and can be transferred immediately when backup resources are available, achieving frequent protection without performance penalty.
4Reliability
If complex differential operations are used in traditional backup methods, then data protection completeness is improved, but operational complexity increases making it difficult to manage
Solution Approach 1:
The patent segments the backup process into simple, manageable components: bitmap-based change tracking and selective block copying. This segmentation replaces complex differential operations with straightforward tracking and copying, reducing operational complexity while maintaining data protection completeness through systematic tracking of all changed data blocks.
Solution Approach 2:
The patent uses simple copying of identified changed data blocks from source to backup storage, replacing complex differential operations. The bitmap tracking system identifies which blocks have changed, and those blocks are directly copied without complex calculations or transformations, significantly simplifying the operational complexity of the backup process.
Data Source
AI summary
One example method includes performing delta operations to protect data. A delta queue is provided that allows a replica volume to be rolled forwards and backwards in time. When rolling the replica volume forward, an undo delta is created such that the replica volume can be moved backwards after being moved forward. When rolling the replica volume backwards, a forward delta is created such that the replica volume can be moved forwards after being moved backwards.