Virtual Storage Partition Data Migration Without Consistency Points
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Solution Overview
Problem
The existing data migration process between storage systems is time-consuming and can lead to application downtime due to the need for consistency points and registry updates, resulting in potential revenue loss and reduced productivity.
Innovation Solution
A method that involves reading the superblock of a read-only replica of a source virtual volume, modifying it to clear the replica flag, and associating it with virtual volume block numbers without initiating a consistency point, allowing the destination virtual volume to become writable, while also modifying the disk group label to reflect the association with the destination storage disk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If consistency points and registry updates are performed during data migration, then data consistency is ensured, but migration time increases and application downtime occurs
Solution Approach 1:
The patent performs preliminary actions by copying data to the destination storage system before the actual migration switch. The read-only replica is created and validated in advance, allowing the system to switch to the destination without performing consistency points during the critical migration window, thus reducing application downtime while maintaining data consistency.
Solution Approach 2:
The migration process is segmented into distinct phases: data copying phase, validation phase, and switch phase. By separating the consistency assurance activities (performed during copying and validation) from the migration switch, the patent eliminates the need for consistency points during the switch operation, thereby reducing migration time without compromising data consistency.
2Ease of operation
If consistency points are initiated to make the destination volume writable, then the replica flag is cleared, but the process operates one volume at a time and exceeds application time-outs
Solution Approach 1:
The patent clears the replica flag and makes the destination volume writable as a preliminary action before the migration switch. By performing this operation in advance during the data copying phase rather than during the switch phase, the system avoids the time-consuming consistency point process during the critical migration window, thereby improving migration speed while maintaining operational ease.
3Ease of operation
If the replication relationship is broken to enable writing to the destination volume, then the volume becomes writable, but time-consuming sub-processes are required
Solution Approach 1:
The patent breaks the replication relationship and clears the replica flag as a preliminary action during the data copying phase. By performing this operation before the migration switch rather than during the switch, the system eliminates the need for time-consuming consistency points and registry updates during the critical migration window, thereby reducing sub-process time while maintaining the ability to make the volume writable when needed.
Data Source
AI summary
A method includes reading a superblock of a read-only replica of a source virtual volume in a source virtual storage partition associated with a source aggregate of a source storage system at the destination storage system, modifying the superblock of the read-only replica in a memory of the destination storage system, and associating the modified superblock with one or more virtual volume block number(s) configured to be previously associated with the superblock of the read-only replica of the source virtual volume without initiating a destination consistency point (DCP) at the destination storage system to render the destination virtual volume writable. The method also includes modifying a disk group label to reflect an association of the destination storage disk with the writable destination virtual volume, and initiating DCP to ensure that the modified superblock and the modified disk group label are flushed to the destination storage disk.