Storage Snapshot Logical-Physical Decoupling for Space Recovery
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Solution Overview
Problem
Remote mirroring in storage systems consumes increasing physical resources due to the long-term maintenance of snapshots, as they continue to occupy storage space even after the source volume is updated, leading to inefficient allocation of resources.
Innovation Solution
A method is introduced to manage physical resources by transmitting snapshots to a remote site, receiving acknowledgments, and disassociating them from physical addresses while maintaining logical associations, allowing for the deletion of snapshot metadata and updating mapping data structures to reflect this disassociation, thereby freeing up physical space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If snapshots are maintained long-term for remote mirroring, then data recovery capability is improved, but physical storage space consumption increases
Solution Approach 1:
The patent extracts the logical association between snapshots and physical addresses from their tight coupling. By separating the logical snapshot metadata from the physical address bindings, the system can maintain snapshots logically for recovery purposes while physically releasing the associated storage space, thus resolving the contradiction between data recovery capability and storage space consumption
Solution Approach 2:
The patent segments the snapshot data structure into two independent parts: logical metadata (snapshot information, timestamps, hierarchy) and physical address bindings. This segmentation allows the system to maintain the logical structure for recovery while independently managing physical space allocation, enabling snapshots to be disassociated from physical addresses to free space
2Stability of the object's composition
If snapshots continuously reference source volume data, then data consistency is maintained, but physical resource allocation increases
Solution Approach 1:
The patent extracts the physical address reference from the snapshot structure, maintaining only the logical association. This allows snapshots to preserve data consistency through logical metadata while eliminating continuous physical resource allocation, as the physical addresses can be released after data is safely replicated to remote storage
Solution Approach 2:
The patent creates a logical copy of the snapshot metadata that references data without maintaining physical bindings. The snapshot information is copied and stored independently, allowing the original physical addresses to be released while the snapshot logical structure remains intact for consistency and recovery purposes
Data Source
AI summary
A method for managing physical resources of a storage system, the method may include transmitting, to a remote site, first information representative of a first snapshot of a logical entity; wherein the first snapshot is associated with first data that is stored in first physical addresses of the storage system; wherein the first physical addresses are mapped to first logical addresses; receiving from the remote site a first acknowledgment indicating that the first information was fully received by the remote site; and disassociating, in response to a reception of the first acknowledgement, the first snapshot from the first physical addresses while maintaining a logical association between the first snapshot and the first logical addresses.