ApsaraDB RDS:Disaster recovery instance preparation

Prerequisites

Create a destination ApsaraDB RDS for PostgreSQL instance that meets the following requirements. For more information, see Create an ApsaraDB RDS for PostgreSQL instance.

• The major engine version of the instance is the same as that of the source instance.

• The instance is a primary instance. Read-only instances cannot be used as disaster recovery instances.

• The billing method must be pay-as-you-go or subscription. Serverless instances are not supported.

• The instance must be empty. Its available storage must be greater than or equal to the total data size of the source database.

Establish network connectivity

Network connectivity solutions

If the source instance supports public access, you can use an Internet NAT Gateway to establish connectivity between the source instance and the VPC of the destination instance. This topic describes how to configure the Internet NAT Gateway for the destination ApsaraDB RDS for PostgreSQL instance.

If your source instance does not support public access, use Cloud Enterprise Network (CEN) to establish network connectivity. For more information, see Use CEN to establish network connectivity.

Configure the destination NAT gateway

1. Log on to the ApsaraDB RDS console and go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the instance ID.

2. In the navigation pane on the left, click Database Connection. On the Database Connection page, view the VPC and vSwitch of the destination instance.

   Hover over the VPC ID to view the vSwitch ID.

3. Click the VPC ID to go to the VPC console.

4. On the Resource Management tab, find the Access to Internet section. Hover over Internet NAT Gateway and click Create Now.

5. On the creation page, configure the following options and click Buy Now.

   Configuration	Description
   Billing Method	The default value is Pay-As-You-Go. You are charged for the resources that you use. For more information, see NAT Gateway billing.
   Instance Name	Set a name for the Internet NAT Gateway instance. The name must be 2 to 128 characters in length, start with a letter or a Chinese character, and can contain digits, underscores (_), and hyphens (-).
   Region	Select the region of the destination ApsaraDB RDS for PostgreSQL instance.
   Resource Group	Select the resource group to which the VPC belongs. For more information, see What is a resource group?
   Network and Zone	Select the VPC and vSwitch of the destination ApsaraDB RDS for PostgreSQL instance.
   Network Type	Select Internet NAT Gateway.
   EIP	Select an elastic IP address (EIP). If you have not purchased an EIP, see Purchase an Internet NAT gateway and an EIP in one-stop mode for a VPC.

6. On the Confirm Order page, confirm the configuration of the Internet NAT Gateway and click Enable Now.

Configure the source instance

Step 1: Create a synchronization account

The source instance requires a database account for synchronization. This account is known as the synchronization account.

1. Connect to the source PostgreSQL instance, create a synchronization account, and set the required permissions. For example, create a synchronization account named replicatoraccount.

   CREATE ROLE replicatoraccount CREATEROLE REPLICATION LOGIN PASSWORD 'your_password';

2. Grant the pg_monitor permission to the synchronization account replicatoraccount.

   GRANT pg_monitor TO replicatoraccount;

3. Connect to the source PostgreSQL instance by using the created synchronization account replicatoraccount and run the following SQL statements to verify that the account has the required permissions.

   1. Run the following SQL statement to create a test user named testreplicator with the REPLICATION permission. If the user is created, the replicatoraccount synchronization account has the required replication permission.

      CREATE USER testreplicator WITH REPLICATION;

      If an error similar to must be superuser to create replication users occurs, use an account that has the SUPERUSER permission to connect to the source instance and grant the SUPERUSER permission to the synchronization account replicatoraccount. For example, run the ALTER USER replicatoraccount WITH SUPERUSER; command.

   2. Delete the test user testreplicator.

      DROP USER IF EXISTS testreplicator;

Step 2: Configure the ECS security group

1. Log on to the ECS console.

2. In the navigation pane on the left, choose Instances & Images > > > Instance.

3. In the top navigation bar, select a region.

4. Find the destination ECS instance and click the instance ID.

5. On the Security Group tab, click the name of the security group.

6. On the Security Group Details page, go to the Access Rules section. On the Inbound tab, click Manually Add. Add the following security group rules.

   The following table describes the security group rules and key parameters.

   Protocol type	Port range	Authorization object
   All ICMP (IPv4)	Source: -1/-1 Destination: -1/-1	The elastic IP address (EIP) of the Internet NAT Gateway, created in the "Establish network connectivity" step. Note On the details page of the destination Internet NAT Gateway, you can view the EIP on the Associated EIP tab.
   TCP	The port of the self-managed PostgreSQL database on the ECS instance. You can run the netstat -a | grep PGSQL command to view the port.

Step 3: Configure the pg_hba.conf file

1. Log on to the ECS instance that hosts the self-managed PostgreSQL database. For more information, see Remotely connect to an ECS instance.

2. Find the location of the pg_hba.conf file.

   Note

   Run this command as the root user.

   find / -name pg_hba.conf

   Sample output:

   /var/lib/pgsql/13/data/pg_hba.conf

3. Go to the directory of the pg_hba.conf file.

   cd /var/lib/pgsql/13/data/

4. Edit the pg_hba.conf file and append the following lines.

   host  all    replicatoraccount  121.XX.XX.XX/32  md5
   host  replication  replicatoraccount  121.XX.XX.XX/32  md5

   Key parameters:

   • replicatoraccount: The synchronization account that you created. For more information, see Step 1: Create a synchronization account.

   • 121.XX.XX.XX: The EIP of the Internet NAT Gateway that is created for the destination ApsaraDB RDS for PostgreSQL instance when you establish network connectivity.

     Note

     On the details page of the destination Internet NAT Gateway, you can view the EIP on the Associated EIP tab.

5. Connect to the source PostgreSQL instance and reload the configuration to apply the changes.

   SELECT pg_reload_conf();

   Sample output:

    pg_reload_conf
   ----------------
    t
   (1 row)

Step 4: Configure the postgresql.conf file

For more information, see Configure the postgresql.conf file.

Step 5: Configure the server firewall

For more information, see Configure the server firewall.