Two-node Instances (Formerly High-availability Edition)

Last updated: 2021-05-24 11:41:32

    TencentDB for MySQL supports three types of architectures: single-node, two-node, and three-node. This document describes the two-node architecture.

    • Two-node instances adopt a highly available one-source-one-replica architecture and support real-time hot backup, automatic detection of failure, and automatic failover.
    • Two-node instances support two resource isolation policies: general and dedicated. For more information, see Resource Isolation Policy.

    Use Cases

    Two-node instances are ideal for industries such as gaming, internet, IoT, retail, e-commerce, logistics, insurance, and securities.


    • The two-node architecture offers two source/replica replication modes: async (default) and semi-sync. You can modify the replication mode or upgrade to the three-node architecture (with the one-source-two-replica strong sync mode) on the instance details page in the console.
    • The two-node architecture supports a complete set of features including read-only instances, security groups, data migration, and multi-AZ deployment. For more information, see Strengths.
    • The two-node architecture achieves a high availability of up to 99.95%. For more information, see TencentDB Service Level Agreement (New Version).
    • The two-node instance provides multiple replicas to guarantee data persistence. The source node data can be synced to the replica node; the source instance data can be synced to the read-only instances (if any). This architecture ensures data security and achieves a data persistence of up to 99.99999%.
    • The two-node architecture deploys data nodes on powerful hardware devices and uses local NVMe SSD disks as underlying storage with an IOPS of up to 240,000 (this value is the test result with MySQL's default page size of 16 KB and for your reference only. The actual value is subject to the specific configuration, page size, and business load).

    Basic Framework Diagram

    Alt text