Diskless Standby Database Replication via Shared De-duplication Storage
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Solution Overview
Problem
Scalable solutions for read-intensive database systems face challenges in maintaining performance and storage efficiency as data grows, particularly in multi-node systems where each standby replica requires independent storage expansion, leading to communication overhead and storage scalability issues.
Innovation Solution
Implementing a multi-node system with shared de-duplication storage and diskless standby database systems, where a single copy of physical database files is stored and updated, and asynchronous notifications ensure data consistency across diskless standbys, allowing for efficient handling of read-only queries without direct coordination among standbys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each standby replica maintains independent storage, then data consistency and reliability are improved, but storage scalability and system complexity worsen
Solution Approach 1:
Multiple standby replicas share a common storage system through de-duplication, merging their storage resources into a single pool. This allows N standby replicas to access the same physical storage without requiring N separate storage systems, thereby improving scalability while maintaining data consistency through the de-duplication mechanism
Solution Approach 2:
The patent uses de-duplication technology to create logical copies of data blocks across multiple standby replicas while storing only one physical copy. This allows each standby to have its own data view for consistency while sharing physical storage resources, resolving the contradiction between reliability and scalability
2Productivity
If multiple standby replicas are deployed, then read performance is improved, but communication overhead and storage needs increase
Solution Approach 1:
Multiple standby replicas share a common storage system, merging their storage requirements into a single pool. This eliminates redundant storage across replicas and reduces overall storage needs while allowing multiple standbys to concurrently handle read operations, thereby improving read performance without proportionally increasing storage requirements
3Reliability
If standby replicas coordinate directly, then data consistency is maintained, but communication overhead increases
Solution Approach 1:
The common storage system acts as an intermediary between multiple standby replicas, providing a centralized mechanism for maintaining data consistency. Instead of direct peer-to-peer coordination which generates communication overhead, each standby interacts with the shared storage through de-duplication metadata, reducing communication requirements while maintaining consistency
Data Source
AI summary
A method and system for replicating database data is provided. One or more standby database replicas can be used for servicing read-only queries, and the amount of storage required is scalable in the size of the primary database storage. One technique is described for combining physical database replication to multiple physical databases residing within a common storage system that performs de-duplication. Having multiple physical databases allows for many read-only queries to be processed, and the de-duplicating storage system provides scalability in the size of the primary database storage. Another technique uses one or more diskless standby database systems that share a read-only copy of physical standby database files. Notification messages provide consistency between each diskless system's in-memory cache and the state of the shared database files. Use of a transaction sequence number ensures that each database system only accesses versions of data blocks that are consistent with a transaction checkpoint.