Imagine you have a banking application and trying to transfer money, suddenly the system crashes. This is where failover testing comes in. Failover testing ensures at the same time, the system checks to find additional backup resources and redirects to other server or browsers without interrupting client.
What is failover testing?
Failover testing is a way to check if a system can switch to backup resources when something goes wrong.
Imagine it like a fire drill for your software. We purposely make the main system fail to see if the backup system can take over quickly and smoothly.
Why do we do this? To make sure that when there’s a problem, users don’t notice anything and everything keeps working as usual.
By practicing failover testing, we ensure that the backup system will work well when needed and understand what to expect during a real issue.
Types of failover test scenarios
Manual failover test:
A person switches the application to the backup infrastructure and verifies it functions correctly.
Automatic failover test:
Using software scripts to automate switching an application to the backup infrastructure when an outage is detected.
– Testing team simulates platform setup as active-passive failover configuration. One system remains active and serves requests while others remain in a passive state, ready to take over in case the active system fails. The passive systems regularly synchronize data with the active system to ensure data consistency. If the active system fails, the passive system automatically transitions into the active state, taking over the workload and ensuring uninterrupted service.
– An example of this failover testing: an online banking system is powered by active-passive failover. The active system handles all incoming transactions, ensuring that customers can access their accounts and perform transactions seamlessly. Meanwhile, the passive system continuously replicates the data from the active system, ensuring that in the event of a failure, the passive system can seamlessly take over. This failover technique provides to both the online bank system and its customers, knowing that their financial transactions are secure and uninterrupted.
Load balancing failover test:
– Distributes network traffic from the original server across multiple servers to improve performance and reliability.
– Testing team simulates platform setup as active-active failover configuration. Multiple systems or nodes are active and actively serving requests simultaneously. This allows workload distribution and load balancing between the active systems, improving overall system performance and enabling high availability. If one system fails, the remaining systems can handle the workload without disruption.
– An example of this failover testing: imagine a cloud-based e-commerce platform that experiences a sudden surge in traffic during a flash sale. With active-active failover, the platform can dynamically allocate the incoming requests across multiple active systems, ensuring that no single system becomes overwhelmed. This not only prevents downtime but also ensures that customers can continue to make purchases smoothly, even during peak demand periods.
Network failover test:
– Testing team simulates a network outage in the system and verifies that the backup infrastructure functions correctly.
– For example, if the system has two data centers, the team might simulate a network outage in one of the data centers to test the failover process.
Hardware failover test:
– Testing team simulates a hardware failure in the system.
– For example, if the system has two servers, the team might simulate a failure in one of the servers to test the failover process.
Other failover tests:
– Testing the failover of a primary database server to a secondary server in the event of a hardware failure or network outage.
– Testing the failover of a cloud service to a secondary data center in the event of a regional outage.
Challenges in Failover Testing
- Complex System Dependencies: Modern software is often a web of interconnected services, making failover scenarios complex.
- Data Synchronization Issues: Ensuring data remains consistent across primary and backup systems can be tricky.
- Resource Allocation: Backup systems need to be as robust as primary systems, which can be resource-intensive.
- Network Configuration: Failover testing often involves intricate network setups that can be difficult to manage.
- Requires a deep understanding of the system architecture and the potential risks involved.
Designing a Failover Strategy
Before beginning failover testing, it’s important to address a few key considerations, like:
- Prepare a well-defined plan that outlines the scope, objectives, and success criteria of your test.
- A backup of your data and an isolated test environment from your production environment should also be established.
- Your plan should include defining the test scenarios and expected outcomes – such as how your database will respond to a power outage, network failure, hardware malfunction, or human error.
- Additionally, you must choose the test method and tools – like manual or automated scripts, native or third-party tools, or cloud-based services.
- Scheduling the test and communicating with stakeholders such as coordinating with team members, clients, or vendors to inform them of the test and its impact.
- Finally, documenting the test procedures and results is essential – recording the steps, timings, errors, and metrics of the test.
Having factored in these considerations, testers can then design test plans around them:
- Analyse system requirements and come up with failover designs accordingly.
- Identify critical systems and components that are critical for maintaining operations. This includes identifying single points of failure and determining which systems should have failover capabilities.
- Assess system dependencies: Understanding the dependencies between systems. Analyze how failure in one system could affect other systems and ensure that failover mechanisms are appropriately implemented to manage these dependencies.
- Decide performance measurement criteria and set benchmarks.
- Select appropriate failover techniques: based on the system requirements and constraints, choose the most suitable failover technique, such as active-active or active-passive failover. Consider factors such as performance, scalability, and cost-effectiveness.
- Implement monitoring and detection mechanisms:
+ Implement robust monitoring and detection mechanisms to promptly detect failures and trigger failover processes.
+ This may involve using monitoring tools, setting up alarms, and configuring automated responses. - Test and validate failover processes:
+ Verify whether the required failover mechanisms activate when failure conditions are correctly detected.
+ Verify whether or not system functionality and data are consistent with the pre-failover state.
+ Testing should simulate various failure scenarios and measure the switchover time to evaluate the effectiveness of the failover strategy.
Conduct a failover test
Conducting a failover test requires specific expertise and roles to ensure it is done effectively and safely. Assume that you have several roles in the project and each person is to take a role. This test requires the collaboration among Tester, IT, Developer:
1. IT, Tester, Developer: Gather your set of systems and tools. Make sure everyone knows their part.
2. Tester: Ensure all your data has an understudy, ready to step in at a moment’s notice.
While doing the failover testing proper back-up and restore mechanism is necessary.
There should be a backup of data so that if any problem occurs during the failover testing the same data can be restored.
3. Tester / IT: Create a testing environment with the conditions or recognized combinations of conditions to cause a system failure.
4. Tester: Run through the failover process in a controlled environment.
5. IT/Developer: Trigger the failover.
6. IT/Developer: Monitor the transition closely. Every second counts.
7. Tester: Once the backup system is live, test all functionalities to ensure the transition is smoothly
8. IT and Developer: Revert to the primary system carefully, ensuring no data loss during the transition.
9. IT, Tester, Developer: Review, analyze the performance. What went well? What tripped up? Learn and improve
10. Tester: Document the success or report regarding any issue. and prepare for the next failover testing
Best Practices of test failover checklist
- Plan Thoroughly: Have a clear, detailed failover plan in place.
- Automate: Use automation tools to make the testing process more efficient and repeatable.
- Monitor: Implement monitoring tools to detect failures as they happen.
- Document: Keep a meticulous record of each test, its results, and any lessons learned.
- Communicate: Ensure all stakeholders understand the failover process and their roles in it.
- Validate: Confirm that the failover system meets all functional and performance requirements.
- Review: Regularly review and update your failover plans to adapt to new system changes.
- Regular Rehearsals: Conduct failover testing regularly to keep your system performance in tune.
- Realistic Scenarios: Test using scenarios that closely mimic potential real-world failures.
- Comprehensive Coverage: Ensure all aspects of the system are tested, leaving no stone unturned.
- Continuous Improvement: Use each test as a learning opportunity to refine and enhance your process.
References
https://testorigen.com/factors-to-consider-and-importance-of-failover-testing/
https://www.qable.io/blog/failover-testing-software-resilience
https://teamhub.com/blog/understanding-failover-in-software-development-a-comprehensive-overview/
https://blog.foreworth.com/how-to-prioritize-performance-with-failover-testing
https://www.linkedin.com/advice/3/what-best-way-test-database-failover-recovery