Logical Drive Resynchronization Using Snapshot Metadata
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Solution Overview
Problem
Existing methods for resynchronizing a logical drive in RAID systems require copying all data from the source to the destination, even if only changes have occurred since the last duplication, leading to wasteful data transfer and increased processing time.
Innovation Solution
A method that tracks changes to the source logical drive and copies only the changed data during the resynchronization process, using snapshots to record metadata and selectively copy updated data to the destination logical drive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all data is copied during resynchronization, then data redundancy is maintained, but data transfer time and processing time increase significantly
Solution Approach 1:
The patent extracts only the changed data blocks from the source logical drive using snapshot metadata, rather than copying all data. The snapshot mechanism identifies which specific data blocks have been modified since the last duplication, allowing the system to transfer only those changed blocks to the destination drive, thereby reducing data transfer time while maintaining data redundancy.
Solution Approach 2:
The patent performs preliminary actions by creating and maintaining snapshot metadata that tracks data changes before the resynchronization operation begins. This preliminary tracking of changed blocks through snapshot mechanisms allows the system to prepare a list of only the data blocks that need to be copied, eliminating unnecessary data transfer and reducing processing time.
2Reliability
If all data is copied during resynchronization, then data consistency is ensured, but processing load and resource consumption increase
Solution Approach 1:
The patent extracts only the changed data blocks identified through snapshot metadata comparison, rather than processing all data blocks. By identifying and copying only the modified blocks, the system reduces the processing load on the source and destination drives while ensuring data consistency through the snapshot-based change tracking mechanism.
Solution Approach 2:
The patent applies partial action by copying only the necessary changed data blocks rather than all data blocks. This selective copying approach reduces processing time and resource consumption while maintaining data consistency, as only the portions of data that have actually changed need to be transferred to ensure the destination is synchronized with the source.
3Reliability
If complete duplication is performed, then backup accuracy is maintained, but system availability decreases due to longer operation time
Solution Approach 1:
The patent extracts only the changed data blocks using snapshot metadata to identify modifications since the last backup. This selective copying approach maintains backup accuracy by ensuring all changes are captured, while significantly reducing the time required for the duplication operation, thereby improving system availability during the backup process.
4Reliability
If unchanged data is overwritten during resynchronization, then data redundancy is maintained, but unnecessary data transfer occurs
Solution Approach 1:
The patent extracts only the changed data blocks by comparing snapshot metadata between the source logical drive and the destination drive. This approach prevents unnecessary overwriting of unchanged data, reducing data transfer efficiency losses while maintaining data redundancy, as the system intelligently identifies and transfers only the blocks that have actually changed.
Data Source
AI summary
There is provided a method of resynchronising a previous duplication, started at a first time, of a source logical drive on a destination logical drive. The method comprises tracking changes to the data on said source logical drive since said first time and starting a resynchronisation operation at a second time later than said first time. The resynchronisation operation comprises copying data from said source logical drive to said destination logical drive by copying only data which has changed since said first time. By providing such a method, the need to copy data which has not changed since the previous duplication operation is alleviated. This reduces the time and processing required to perform the resynchronisation operation by eliminating unnecessary transfer of data which has not changed since the earlier duplication.