Persistent Point in Time Data Retention During Volume Migration
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Solution Overview
Problem
During data migration between storage systems, transferring all persistent point in time data can lead to increased unavailability of storage systems, causing user access issues and dissatisfaction if the migrated data does not contain the unaltered data sought by users.
Innovation Solution
The use of a collective persistent point in time data map allows for the reliable transfer of volumes between storage systems with minimal unavailability, by organizing and transmitting this map along with the volume, ensuring that user access is maintained and all necessary data is retained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all persistent point in time data is transferred during volume migration, then data integrity is maintained, but storage system unavailability increases
Solution Approach 1:
The patent segments persistent point in time data into two categories: data to be migrated with the volume and data to be retained on the source system. The migration process selectively transfers only the necessary portion of PPT data, while the source system maintains the complete set of PPT data throughout the migration process, ensuring data integrity without requiring full data transfer.
Solution Approach 2:
The source storage system retains all persistent point in time data before and during the migration process. This preliminary retention ensures that if any issues arise during migration or if users need to access historical data, the complete PPT data is already available on the source system, eliminating the need to transfer all PPT data to the destination system.
2Productivity
If a portion of persistent point in time data is transferred, then storage system availability is improved, but data completeness may be compromised
Solution Approach 1:
The source storage system retains all persistent point in time data before and during the migration process. This preliminary retention ensures that if any issues arise during migration or if users need to access historical data, the complete PPT data is already available on the source system, eliminating the need to transfer all PPT data to the destination system.
Solution Approach 2:
The source storage system acts as an intermediary that maintains the complete set of persistent point in time data during migration. Users can access PPT data from the source system during the transition period, and the source system serves as a backup ensuring data completeness even while the destination system receives only the current volume data.
3Ease of operation
If persistent point in time data is retained on the source system during migration, then user access to historical data is maintained, but data synchronization complexity increases
Solution Approach 1:
The patent extracts the requirement to transfer all persistent point in time data from the migration process. Instead of moving all PPT data to the destination system, the solution separates the migration of current volume data from the retention of historical PPT data on the source system, simplifying the synchronization process while maintaining user access capabilities.
Solution Approach 2:
The source storage system continues to serve PPT data requests during migration without requiring complex coordination with the destination system. Users accessing historical data are automatically directed to the source system, which handles these requests independently, eliminating the need for complex inter-system synchronization protocols.
Data Source
AI summary
Provided is a method and system for performing volume migrations while retaining persistent point in time data of the migrated volume. Specifically, by using a collective persistent point in time data map that describes a collection of persistent point in time data of a volume to be migrated, the collective persistent point in time data map and volume data can be migrated during a quiesced period of user activity. Then, during a non-quiesced period of user activity, the persistent point in time data can be transferred to the location of the migrated volume in real-time.