Storage Control Apparatus Data Synchronization During Backup
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Solution Overview
Problem
The reliability of data stored in a replica volume decreases when mirror processing is temporarily stopped for backup, leading to potential data inconsistencies and reduced reliability during data restoration.
Innovation Solution
A control apparatus that manages data between two volumes under equivalent and non-equivalent states, using bitmaps to track data synchronization and copying only updated portions to ensure data integrity and reliability during backup and recovery processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mirror processing is temporarily stopped for backup, then backup operation can be performed, but data reliability decreases due to potential data inconsistencies
Solution Approach 1:
The system performs preliminary actions by recording write requests in a write request management table before executing the backup operation. This allows the system to track which data blocks have been modified during the non-equivalent state, ensuring that only necessary data is copied back after backup, thereby maintaining data reliability while enabling backup operations.
Solution Approach 2:
The system implements feedback mechanisms through bitmaps and write request management tables that continuously track the state of data blocks. The bitmap records whether data blocks have been written during non-equivalent state, and this information feeds back to the copy control unit to determine whether copy-back operations are necessary, ensuring data consistency is maintained throughout the backup process.
2Reliability
If data is copied back after backup, then data reliability is restored, but processing time increases
Solution Approach 1:
Instead of copying all data blocks back after backup, the system performs partial action by using bitmaps to identify only those specific blocks that require copy-back operations. The copy control unit checks the bitmap and executes copy-back only for blocks marked as needing restoration, significantly reducing processing time while maintaining data reliability.
Solution Approach 2:
The system segments the data storage into multiple blocks and tracks each block's state independently using bitmaps and write request management tables. This segmentation allows the system to process only the necessary portions of data during copy-back operations rather than treating the entire dataset as a single unit, thereby reducing overall processing time.
3Reliability
If write requests are recorded during non-equivalent state, then data consistency is maintained, but memory usage increases
Solution Approach 1:
The system applies local quality by using bitmaps that record write status at the block level rather than tracking entire volumes. This localized tracking approach uses minimal memory resources while maintaining data consistency, as only the necessary bitmap bits and relevant write request information are stored in memory during non-equivalent state.
Data Source
AI summary
A control apparatus includes a processor. The processor determines, upon detecting a read error on a first volume of a storage under a non-equivalent state, a first storage area in which the read error has occurred. The first storage area is included in the first volume. The processor determines whether a write process has been conducted on the first storage area under the non-equivalent state. The processor determines whether a write process has been conducted on a second storage area under the non-equivalent state. The second storage area is included in a second volume of a storage and corresponds to the first storage area. The processor copies data stored in the second storage area to the first storage area when no write process has been conducted on the first storage area and the second storage area under the non-equivalent state.