ApsaraDB RDS:RDS Cluster Edition

Architecture

RDS Cluster Edition is supported for ApsaraDB RDS for MySQL instances that run MySQL 5.7 and MySQL 8.0. An RDS cluster uses the HA architecture of one primary node and multiple secondary nodes. The following figure shows the architecture.

Benefits

More cost-effective

Secondary nodes in an RDS cluster are readable. You do not need to create read-only RDS clusters. This linearly increases the read capability of the RDS cluster and reduces resource overheads and costs. If you use RDS High-availability Edition and you want to increase the read capability of your RDS instance, you must create read-only RDS instances. Compared with RDS High-availability Edition, RDS Cluster Edition reduces the costs by 40%.

You can use one of the following methods to access the secondary nodes in an RDS cluster:

• Read-only routing endpoint: You can create a read-only routing endpoint for an RDS cluster free of charge and add multiple secondary nodes to the read-only routing endpoint. Then, you can specify read weights for the secondary nodes to balance loads. For more information, see View and manage instance endpoints and ports.

• Database proxy: You can enable the database proxy feature for an RDS cluster to implement read/write splitting on the primary and secondary nodes in the RDS cluster. Compared with the read-only routing endpoint, the database proxy feature supports advanced capabilities, including automatic read/write splitting, persistent connections, connection pooling, latency threshold, and transaction splitting. For more information, see Enable the dedicated proxy feature and What are database proxies?

  Note

  • Starting June 25, 2024, if you create a primary RDS instance that runs RDS Cluster Edition, the general-purpose database proxies are included by default at no additional cost. For more information, see Billing rules for database proxies and What are database proxies?.

  • If you have higher requirements on the stability of database proxies, you can change the proxy type from general-purpose to dedicated. For more information, see Change the database proxy type and number of database proxies and What are database proxies?

  • You can disable the dedicated proxy feature at any time. For more information, see Disable the dedicated proxy feature.

More flexible

• Flexible node deployment

  Compared with RDS Basic Edition and RDS High-availability Edition, RDS Cluster Edition supports node topology management. After you create an RDS cluster, you can add or delete nodes based on your business requirements in a more cost-effective manner. For more information, see Add a node to an ApsaraDB RDS for MySQL cluster and Delete a node from an ApsaraDB RDS for MySQL cluster.

• Node-level monitoring

  RDS Cluster Edition supports node-level monitoring. You can view the status of each node in an RDS cluster.

More reliable

• Cross-zone disaster recovery

  In RDS High-availability Edition, one primary instance and one secondary instance are provisioned to ensure HA. In RDS Cluster Edition, all secondary nodes in an RDS cluster can be used for disaster recovery. We recommend that you deploy secondary nodes in different zones to achieve cross-zone disaster recovery.

• Strong data consistency

  If more than three nodes are deployed in an RDS cluster, the MGR mode can be used for the RDS cluster. MGR is developed based on Paxos, a distributed consensus protocol. Before a transaction is committed on the primary node, the system sends the data of the transaction to secondary nodes and ensures that a majority of secondary nodes receive the data. Compared with semi-synchronous replication and asynchronous replication, MGR ensures strong data consistency and higher data security.

• More reliable secondary nodes

  The Alibaba Cloud technical team uses cloud native technologies to perform in-depth optimizations on ApsaraDB RDS. This improves the reliability of the secondary nodes in RDS clusters.

  • The RDS high-availability system is reconstructed. This reduces the time that is required to detect faults on the secondary nodes from minute-granularity to second-granularity.

  • The single-digit second backup feature that is provided by Elastic Block Storage (EBS) is used. This reduces the time that is required to restore data from dozens of minutes to 1 minute and allows a secondary node to recover from faults within 10 minutes in 99% of use cases.

Scenarios

RDS Cluster Edition is suitable for large and medium-sized enterprises whose production databases need to process a large number of read requests during peak hours or need to perform intelligent data analysis. These enterprises include online retailers, automobile enterprises, education enterprises, and Enterprise Resource Planning (ERP) service providers.

Scenarios of RDS Cluster Edition for ApsaraDB RDS for MySQL