Multi-AZ DR Testing for Oracle RDS using Oracle Application Express

Overview

This blog continues my First Blog, Multi-AZ DR Testing for Oracle RDS using Oracle Application Express – Part 1. Earlier, we installed Multi AZ Oracle RDS with the Multi-AZ option and configured the perquisites for Oracle Apex Application. In this part, we will install the Oracle Apex application and test the Failover Mechanism.

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Step-by-Step Guide

In this section, we will Install and configure Apex and ORDS, then test the Multi-AZ Failover of AWS Oracle RDS.

Installing APEX and ORDS

Step 1: Download Oracle Apex

Go to the Oracle Apex page and Download apex using the command,

wget https://download.oracle.com/otn_software/apex/apex_22.2_en.zip

1	wget https://download.oracle.com/otn_software/apex/apex_22.2_en.zip

Please execute the below commands to install and configure ORDS for use with Oracle APEX

mkdir /home/apexuser/ORDS
cd /home/apexuser/ORDS

1 2	mkdir /home/apexuser/ORDS cd /home/apexuser/ORDS

Download Oracle REST data services,

wget https://download.oracle.com/otn_software/java/ords/ords-21.4.0.348.1956.zip
unzip ords-21.4.0.348.1956.zip

1 2	wget https://download.oracle.com/otn_software/java/ords/ords-21.4.0.348.1956.zip unzip ords-21.4.0.348.1956.zip

Step 2: Download and Install ORDS

Download and install ORDS schema using the ords.war file.

java -jar ords.war install advanced

1	java -jar ords.war install advanced

Please provide the location to store configuration data: /home/apexuser/ORDS
Enter the database connection type,Enter a value for [1]. Basic [2] TNS [3] Personalised URL [1]: 1Enter the database server name [localhost] here: drdbinstance1.cwtekktkfr7s.us-east-1.rds.amazonaws.comEnter [1521] as the database listen port: 1521Enter 1 for the database service name or 2 for the database SID [1]: 2
Enter 1 to verify/install the Oracle REST Data Services schema or 2 to skip this step.

Enter the ORDS_PUBLIC_USER database password:

Password confirmation:

ADMIN is the administrator’s username.

step2

step2b

Set a password for the APEX admin To do this, use SQL*Plus to connect to your DB instance as the master user, and then run the following commands.

EXEC rdsadmin.rdsadmin_util.grant_apex_admin_role;
grant APEX_ADMINISTRATOR_ROLE to ADMIN;
@/home/apexuser/apex/apxchpwd.sql

EXEC rdsadmin.rdsadmin_util.grant_apex_admin_role;

grant APEX_ADMINISTRATOR_ROLE to ADMIN;

@/home/apexuser/apex/apxchpwd.sql

Step 3: Start ORDS Listener

Start the ORDS listener. Run the following code.
Enter the following URL in your browser,

ip:8080/ords

1	ip:8080/ords

step3

Our application is ready. Now we need to do FIS Test.

Step 4: Forced Failover Using FIS Test

Go to FIS Console and select Create Experiment template

step4

Provide Description and Name

step4b

Click on Add target and put some Name,
Choose Resource type as aws:rds:db
Then select the RDS as the Resource ID

step4c

Now click on Actions.
Provide some name
Select action type as aws:rds:failover-db-instances
Then click on save

step4d

Create experiment template

step4e

Please go to the browser and put ip:8080/ords

step4f

Keep the session alive by refreshing the page.
Go to FIS Console, select our experiment template, and click Start Experiment.

step4g

step4h

Conclusion

FIS Test started, and Primary RDS started to reboot and failover to the secondary db.

The connection got freeze for 60 seconds during the failover time.

If you enable Multi-AZ, Amazon RDS automatically moves to a standby replica in a different Availability Zone. The amount of time it takes for the failover to finish depends on the activity of the database and other factors at the moment the primary DB instance stops working. Normal failover times range from 60 to 120 seconds. However, large transactions or a protracted recovery procedure may lengthen the failover duration. It can take some extra time after the failover is finished for the RDS interface to display the new Availability Zone. Amazon RDS handles failovers automatically to restore database operations as soon as feasible without administrative intervention.

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FAQs

1. Can I start a "forced failover" for deploying Multi-AZ DB instances?

ANS: – Amazon RDS will automatically failover without user intervention in several failure scenarios. Also, Amazon RDS allows you to start a failover when restarting your instance. You can utilize this feature using the RebootDBInstance API call or the AWS Management Console.

2. My Primary Instance is now situated in a separate Availability Zone from my other AWS resources (such as EC2 instances) because of the failover. Do I need to worry about latency?

ANS: – Availability Zones are meant to communicate with other Availability Zones in the same Region as quickly as possible. You may also want to consider architecting your application and other AWS resources with redundancy across different Availability Zones to make your application resilient in an Availability Zone failure. Multi-AZ deployments meet this database tier requirement without your management involvement.

3. How do automated backups and DB snapshots work with my Multi-AZ deployment?

ANS: – You engage with automated backup, and DB Snapshot features in the same way whether you are using a standard deployment in a Single-AZ or Multi-AZ deployment. In a Multi-AZ configuration, automated backups and DB Snapshots are taken from the standby to avoid I/O interruption on the main. Please remember that Single-AZ and Multi-AZ deployments may cause higher I/O latency, typically lasting a few minutes. A restore operation (point-in-time restore or restore from DB Snapshot) is also available in ordinary Single-AZ deployments. To deploy new DB instances, utilize the RestoreDBInstanceFromSnapshot or RestoreDBInstanceToPointInTime APIs. These new DB instance deployments can be either standard or Multi-AZ, regardless of whether the source backup was begun on a standard or Multi-AZ deployment.