Virtual Snapshot System Reduces Storage I/O Load
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Solution Overview
Problem
Existing disk storage systems face delays in access for local users due to the time required for snapshot replication at multiple local sites, which also increases the I/O load on the source data, slowing down the system and delaying data recovery in case of failures.
Innovation Solution
The method involves creating virtual snapshots at local sites, allowing immediate access to users by directing them to the source snapshot until the actual replication is complete, thereby reducing delays and I/O load by using a system that replicates snapshots from the closest or most complete site.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If snapshots are replicated at local sites, then local users can access snapshots, but access is delayed until replication completes and I/O load on source increases
Solution Approach 1:
The system creates a virtual snapshot immediately when the source snapshot is created, before the actual replication to local sites is complete. This preliminary action allows local users to access the snapshot right away through the virtual snapshot, eliminating the waiting period until replication finishes. The virtual snapshot serves as a placeholder that provides immediate access while the actual data replication occurs in the background.
Solution Approach 2:
The virtual snapshot acts as an intermediary between local users and the source snapshot. Instead of users directly accessing the source snapshot or waiting for local replication, the virtual snapshot mediates by providing immediate local access that eventually gets replaced by the actual replicated snapshot. This intermediary mechanism resolves the conflict between immediate access and complete replication.
2Ease of operation
If snapshots are replicated at numerous local sites, then local users can access snapshots locally, but significant I/O load is created on the source
Solution Approach 1:
The system segments the snapshot access function into two parts: the virtual snapshot that provides immediate local access with minimal I/O load, and the actual replication process that occurs separately. By segmenting these functions, the system allows multiple local sites to access snapshots without each site creating proportional I/O load on the source, as the virtual snapshots handle access requests locally.
Solution Approach 2:
The system creates a virtual copy (virtual snapshot) at each local site that mimics the functionality of the actual snapshot without requiring the full data replication. This copying approach allows local users to access snapshot data immediately through the virtual copy, reducing the urgency and volume of I/O operations needed from the source system.
3Adaptability or versatility
If snapshots are replicated from a single source to multiple local sites, then snapshots are available locally, but system performance slows due to I/O load
Solution Approach 1:
The system performs preliminary creation of virtual snapshots at all local sites before the actual data replication is complete. This allows the snapshot distribution functionality to be established immediately, enabling adaptability and versatility in snapshot access across multiple sites without the performance penalty of simultaneous full replication to all sites.
Data Source
AI summary
The present disclosure relates generally to a method and system for creating, replicating, and providing access to virtual snapshots of a disk storage block of a disk storage system or subsystem. In one embodiment, the present disclosure relates to a virtual snapshot accessible to local users of a local data storage device. The virtual snapshot may direct local users to a snapshot stored on computer-readable storage medium at a remote data storage site, but give the appearance as if data of the corresponding snapshot is stored locally. The virtual snapshot is replaced by replication of the snapshot from the remote data storage site to the local data storage device. Each snapshot may relate to data of a logical data volume, the logical data volume being an abstraction of data blocks from one or more physical storage devices.