Remote Copy Consistency Group Composition Change
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Solution Overview
Problem
Existing remote copying systems face challenges in efficiently changing the composition of a consistency group without releasing volume pairs, which requires significant time and labor, and can lead to data inconsistency and recovery issues.
Innovation Solution
The remote copying system allows for the easy modification of a consistency group composition by performing a predetermined formalization operation after the change, using sequence numbers to ensure data consistency and order, even when volume pairs are not released.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the composition of a consistency group is changed by releasing volume pairs, then the consistency group composition can be modified, but significant time and labor are required and data inconsistency may occur
Solution Approach 1:
The patent applies preliminary action by performing a formalization operation before actually changing the consistency group composition. The system issues a formalization notification to the secondary storage system beforehand, ensuring that data is properly synchronized and formatted before the volume pairs are released and re-established. This preliminary formalization step prevents data inconsistency and reduces the overall time required for composition changes.
2Adaptability or versatility
If the composition of a consistency group is changed by releasing volume pairs, then the consistency group composition can be modified, but data inconsistency and recovery issues may arise
Solution Approach 1:
The patent performs a formalization operation before changing the consistency group composition. The primary storage system issues a formalization notification to the secondary storage system, ensuring that all data is properly synchronized and formatted before the volume pairs are released. This preliminary action guarantees data consistency and prevents recovery issues.
Solution Approach 2:
The patent implements feedback by having the secondary storage system send a formalization completion notification back to the primary storage system. This feedback mechanism confirms that the formalization operation has been successfully completed, ensuring that data consistency is maintained before the consistency group composition is actually changed.
3Speed
If multiple communication lines are provided in parallel for asynchronous RC, then data transfer speed is improved, but data may be received in incorrect order
Solution Approach 1:
The patent applies parameter changes by introducing sequence numbers as an additional parameter to the data transmission process. Each data block is tagged with its sequence number, allowing the secondary storage system to reorder received data correctly even when multiple communication lines are used in parallel. This parameter addition maintains data integrity while preserving the speed benefits of parallel communication.
Data Source
AI summary
Composition of a consistency group is changed easily without releasing a volume pair of the consistency group concerning a remote copying system and a remote copying method using a sequence number. In order to change the composition of the consistency group, predetermined data sent from a data sending side after the relevant change is received. At that time, a reflection operation of the predetermined data on a logical storage area is started on a data receiving side after reflection of the predetermined data sent from the data sending side before the relevant change on the logical storage area is terminated.