Storage System Differential Bitmap Copy-After-Write
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Solution Overview
Problem
Existing snapshot differential copying technologies fail to efficiently omit saving data elements that are no longer snapshot configuration elements, leading to increased processing time and unnecessary data copying.
Innovation Solution
A storage system with a processor, cache memory, and storage apparatus that omits copying data from one logical volume to another when the data is not yet copied to the secondary volume, using differential bitmaps and Copy-After-Write (CAW) processing to manage data copying efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data copying is performed for every snapshot configuration element, then snapshot accuracy is improved, but processing time increases
Solution Approach 1:
The patent extracts and identifies only the necessary snapshot configuration elements that actually require copying, separating them from other data elements. By using metadata markers and differential bitmaps, the system extracts only the essential data elements that need to be copied to the secondary volume, avoiding unnecessary copying operations and reducing processing time while maintaining snapshot accuracy.
Solution Approach 2:
The patent applies partial action by copying only the necessary snapshot configuration elements rather than all data elements. Through the use of differential bitmaps and metadata tracking, the system performs partial copying of only those data elements that are actually required for snapshot integrity, thereby reducing overall processing time while maintaining sufficient snapshot accuracy.
2Loss of time
If data copying is omitted for non-snapshot elements, then processing time is reduced, but snapshot integrity may be compromised
Solution Approach 1:
The patent implements feedback mechanisms through metadata markers and differential bitmaps that continuously track which data elements are snapshot configuration elements. This feedback system ensures that only appropriate data elements are copied, providing verification that snapshot integrity is maintained while avoiding unnecessary copying operations, thus reducing processing time without compromising reliability.
Solution Approach 2:
The patent replaces the mechanical approach of copying all data elements with an intelligent system that uses metadata tracking and differential bitmaps to identify and copy only necessary elements. This substitution of mechanical copying with intelligent selection reduces processing time while maintaining snapshot integrity through precise tracking of configuration elements.
3Reliability
If all data elements are copied to secondary volume, then snapshot completeness is improved, but system load increases
Solution Approach 1:
The patent extracts only the essential snapshot configuration elements from the total data set using metadata markers and differential bitmaps. By identifying and separating only those data elements that are necessary for snapshot completeness, the system avoids the excessive load of copying all data elements while maintaining sufficient snapshot completeness for operational requirements.
Solution Approach 2:
The patent applies partial action by copying only the necessary portion of data elements required for snapshot completeness rather than all data elements. Through intelligent identification using differential bitmaps and metadata, the system performs partial copying that maintains snapshot completeness for critical operations while significantly reducing system load compared to complete data copying.
Data Source
AI summary
When the storage system according to the present invention receives a request for writing new data to a first logical volume after having received a first pair creating request, the storage system stores the new data in a cache memory. Then when the storage system subsequently receives a second pair creating request, even if the cache memory still has stored therein the data identical to the data that was stored on the first logical volume at the point in time when the storage system received the first pair formation request, and even if this identical data has not yet been copied to the second logical volume, the storage system omits to copy this identical data to the second logical volume.