Updated on 2025-07-23 GMT+08:00

Creating a Read Replica

Scenarios

Read replicas enhance the read capabilities and reduce the load on your DB instances.

After an RDS for MariaDB instance is created, you can create read replicas for it as required.

Constraints

A maximum of five read replicas can be created for a DB instance. To create more read replicas, submit a service ticket to request permissions. You can create up to 10 read replicas for each DB instance.

For details about how to create read replicas in batches, see Creating Read Replicas in Batches.

Procedure

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and a project.
  3. Click in the upper left corner of the page and choose Databases > Relational Database Service.
  4. On the Instances page, locate the target DB instance and choose More > Create Read Replica in the Operation column.
  5. On the displayed page, configure required parameters and click Next.

    Table 1 Basic information

    Parameter

    Description

    Billing Mode

    Yearly/monthly billing and pay-per-use billing are supported.

    Region

    By default, read replicas are in the same region as your DB instance.

    DB Instance Name

    Must start with a letter and consist of 4 to 64 characters. Only letters (case-sensitive), digits, hyphens (-), and underscores (_) are allowed.

    DB Engine

    Same as the DB engine of your DB instance by default and cannot be changed.

    DB Engine Version

    Same as the DB engine version of your DB instance by default and cannot be changed.

    Storage Type

    Determines the DB instance read/write speed. The higher the maximum throughput is, the higher the DB instance read/write speed can be.

    Cloud SSD: cloud disks used to decouple storage from compute. The maximum throughput is 350 MB/s.

    AZ

    RDS for MariaDB allows you to deploy your DB instance and read replicas in a single AZ or across AZs to improve reliability.

    Table 2 Instance specifications

    Parameter

    Description

    Instance Class

    Refers to the vCPU and memory of a DB instance. Different instance classes support different numbers of database connections and maximum IOPS.

    After a DB instance is created, you can change its instance class. For details, see Changing a DB Instance Class.

    Storage Space

    Contains the system overhead required for inodes, reserved blocks, and database operation.

    By default, storage space of a read replica is the same as that of the primary DB instance.

    Table 3 Network

    Parameter

    Description

    VPC

    Same as the primary DB instance's VPC.

    Subnet

    Same as the primary DB instance's subnet. A floating IP address is automatically assigned when you create a read replica. You can also enter an unused floating IP address in the subnet CIDR block. After the read replica is created, you can change the floating IP address.

    Security Group

    Same as the primary DB instance's security group.

    Table 4 Enterprise project and tags

    Parameter

    Description

    Enterprise Project

    If your account has been associated with an enterprise project, select the target project from the Enterprise Project drop-down list.

    For more information about enterprise projects, see Enterprise Management User Guide.

    Tag

    Optional. Tags help you easily identify and manage your read replicas. A maximum of 20 tags can be added for each read replica.

    After a read replica is created, you can view its tag details on the Tags page. For details, see Managing Tags.

    Table 5 Yearly/monthly read replicas

    Parameter

    Description

    Required Duration

    The system will automatically calculate the configuration fee based on the selected required duration. The longer the required duration is, the larger discount you will enjoy.

    Auto-renew

    • By default, this option is not selected.
    • If you select this option, the auto-renew cycle is determined by the selected required duration.

  6. Confirm specifications.

    • If you need to modify your settings, click Previous.
    • If you do not need to modify your settings, click Submit for pay-per-use read replicas.
    • For yearly/monthly read replicas, click Pay Now.

  7. After a read replica is created, you can view and manage it.

    You can view the detailed progress and result of the task on the Task Center page. For details, see Task Center.

Follow-up Operations

Managing a Read Replica