ApsaraDB RDS:Global Active Database

Overview

To ensure business continuity and high availability (HA), ApsaraDB RDS for PostgreSQL supports Global Active Database (GAD) to provide disaster recovery capabilities. This feature delivers a one-stop, cost-effective cross-region disaster recovery solution based on Data Transmission Service (DTS) and the native physical replication feature of RDS for PostgreSQL. In the solution, a primary instance and a secondary instance are added to a GAD instance group. Data is synchronized from the primary instance to the secondary instance in real time by using DTS. This achieves cross-region disaster recovery and allows users to access data from the nearest region.

Architecture

Scenarios

GAD is applicable for the following scenarios:

• Cross-region disaster recovery

  Some businesses have extremely high requirements on availability. To avoid region-level failures, the database system in these businesses must implement cross-region disaster recovery to ensure availability and recovery time objective (RTO).

• Cross-region read-only request handling

  In some businesses, users need to query data from the nearest region. The data system in these businesses must handle the cross-region read-only requests.

Benefits

• Secure and reliable

  • Implemented based on the native replication feature provided by RDS for PostgreSQL, GAD offers stable performance and is fully compatible with the database services of Alibaba Cloud.

  • Supported by the guaranteed Service Level Agreement (SLA) provided by RDS and DTS, GAD can ensure the availability and security of databases and synchronization tasks.

• Convenient and easy to use

  • You can quickly create and configure a GAD instance group for disaster recovery in the product-ready RDS console.

  • GAD provides various capabilities to help you implement disaster recovery through the complete lifecycle, such as disaster recovery assessment, one-click promotion, and latency display.

• Cost-effective

  • The secondary instance (disaster recovery instance) in GAD instance groups supports cost-effective RDS series and editions, such as Yitian RDS instances and RDS instances that run Basic Edition .

  • The data synchronization in GAD instance groups is implemented by DTS. The bandwidth used for data synchronization can be automatically scaled using a serverless approach. You are charged only for the resources that are actually used when you use GAD.

Limits

Billing

When you use GAD, you are charged for the RDS instance that you newly purchase to create the GAD instance group and the data synchronization capability provided by DTS. If you create a GAD instance group by using instances that you have already purchased, you are charged only for DTS.

• Fees for RDS instances newly purchased for GAD

  If you newly purchase an RDS for PostgreSQL instance and use it as the primary or secondary instance of a GAD instance group, you are charged fees for the billable items of the instance, such as instance type and storage capacity, on a subscription or pay-as-you-go basis.

• Fees for data synchronization

  When you add a secondary instance to a GAD instance group, a one-way data synchronization task between the primary and secondary instances is created. You are charged fees for the tasks based on the region of the instances, task type, the number of tasks, and the usage duration of the task. You can calculate the fees by using the following formula:

  Fees for data synchronization = Unit price for data synchronization task x Number of tasks x task usage duration

  The unit price for one-way synchronization task is USD 0.187969924812/hour/task.

How to use

• Method 1: Purchase an RDS for PostgreSQL instance and add it to a GAD instance group as the secondary instance.

  1. Create a GAD instance group.

  2. Create an RDS for PostgreSQL instance and add it to the GAD instance group as the secondary instance.

• Method 2: Add an existing RDS for PostgreSQL instance to a GAD instance group as the secondary instance.

  1. Create a GAD instance group.

  2. Add an existing RDS for PostgreSQL instance to the GAD instance group as the secondary instance. For more information, see Method 2: Add an existing instance as a secondary instance.

• Method 3: Create a GAD instance group by adding a Disaster Recovery Instance on the Basic Information page of an existing RDS for PostgreSQL.

  1. On the Basic Information page of an existing RDS for PostgreSQL instance, create a GAD instance group by clicking Add for Disaster Recovery Instance.

  2. Create a new RDS for PostgreSQL instance and add it to the GAD instance group or add an existing RDS for PostgreSQL instance to the GAD instance group as the secondary instance. For more information, see Method 1: Create a new instance and add it as the secondary instance or Method 2: Add an existing instance as a secondary instance.