A Guide to Availability Testing for Your Software in 2025

Ensuring high system uptime requires a structured method for availability testing. This guide explains the tools, metrics, and scenarios for effective availability testing. QASource supports testing to help deliver consistently accessible software solutions.

Today's modern applications depend on various servers, internal and external network connections, data centers, operational procedures, and a wide range of other infrastructural services, which must all function consistently and in unison. Here, a constant flow of information is excellent for business, and any interruption loses the corporation money; as a result, developing high-availability apps becomes a crucial business strategy.

Availability testing can assist in solving this problem. Whether you’re developing a new application or trying to improve the performance of an existing one, availability testing is an integral part of the process. You must know how your software will perform under different conditions and environments. Ultimately, it’s valuable for providing a great experience for users and avoiding downtime.

What is Availability Testing, and Its Types?

Availability testing is performance testing conducted to check whether a system can meet the required availability SLA (service-level agreement). This testing aims to ensure that the system can remain operational during peak load times and recover quickly from any unexpected failures.

It’s important to note that availability testing in software testing is not the same as load testing, which focuses on assessing the system’s ability to handle heavy loads. Instead, availability testing assesses the system’s ability to remain operational under normal and peak load conditions.

Types of Availability Testing

• Ping Testing of URL: This type of availability testing is used to check the accessibility or responsiveness of a system. In this test, we send ICMP (Internet Control Message Protocol) echo request packets to the server and wait for the ICMP echo reply. If we don’t get a reply from the server, it means that either the server is down or there is a problem with network connectivity.

• Multi-step Web Test: A multi-step web test is a type of availability testing in software testing that simulates real user traffic patterns to identify potential issues with websites or web-based applications. In a multi-step web test, virtual users (i.e., software agents) are generated, and each follows a defined scenario, such as buying a product on an eCommerce site.

  Multi-step web tests aim to find performance bottlenecks that could impact the user experience. For example, a slow response time for a particular page could cause users to abandon the site altogether.

• Standard Test: A standard test determines the percentage of time that a system or application is available for use. It does not consider any downtime due to planned maintenance or unplanned outages. As such, it’s a good measure of how well the system or application can tolerate unplanned downtime. The standard test measures availability as a percentage of time the system or application is available for use, divided by the total time period being considered.

• Custom Track Availability Test: A custom track availability test is a test method used to determine whether a software system can continue to function while being bombarded with requests. This type of test is commonly used to assess web-based applications.

What Are the Core Components of Availability Testing?

Availability testing offers the following features:

• Continuous Testing: Continuous testing is a process of running tests on software as new code changes are made. This allows for immediate feedback on the impact of code changes and can help to identify issues early in the development process.

• Calculate Efficiency: This can be done by taking the total number of transactions completed over a period of time and dividing it by the total number of requests made during that same time period. This will give you your transaction success rate, which you can use to compare different software systems.

• Automated Test Cases: One of the features of availability testing is that it can be automated. This means you can create test cases and then run them automatically. This can save you a lot of time and effort and ensure that your tests are always up-to-date.

• Continuous Monitoring: To ensure that your software is always available, you need to have a plan in place for continuous monitoring. This means having a system in place that can check the availability of your software at regular intervals and alert you if there are any issues.

Why is Availability Testing Important?

Testing for availability is essential because downtime can significantly impact a business. For example, the company will lose out on potential sales if an eCommerce site is down. In addition, downtime can lead to lost productivity and decreased customer satisfaction.

• Prevents Downtime: Ensures the software stays accessible without unexpected failures. This helps maintain uninterrupted operations and service availability.

• Improves User Experience: Keeps applications running smoothly, reducing frustration. Users can rely on the system without delays or disruptions.

• Identifies Weak Points: Detects potential failures in infrastructure, networks, or dependencies. Early detection helps prevent major system crashes.

• Enhances System Reliability: Ensures the application can handle different conditions, like high traffic. This keeps performance stable and consistent.

• Minimizes Business Losses: Prevents financial losses due to downtime or system failures. A reliable system helps maintain revenue and customer trust.

• Supports Business Continuity: Keeps critical services running even in unexpected situations. This ensures smooth operations without costly interruptions.

• Optimizes Infrastructure: Helps manage dependencies across servers, databases, and third-party services. Fine-tuning these elements improves system stability.

How Does Availability Testing Impact User Experience

Availability testing aims to ensure a software system can continue functioning during and after unexpected events, such as power outages or network failures. This type of testing is essential because it directly impacts the user experience — if a system goes down, users will be unable to access it.

• Ensures Consistent Access: Users can rely on the software without unexpected downtimes. This builds trust and improves satisfaction.

• Reduces Frustration: Frequent crashes or slow performance annoy users. A stable system keeps interactions smooth and stress-free.

• Improves Performance: Availability testing helps identify issues affecting speed and responsiveness. A well-optimized system enhances user engagement.

• Enhances Reliability: Users expect software to work when they need it. Ensuring high availability prevents disruptions and keeps them engaged.

• Boosts Retention Rates: If an application is reliable, users are more likely to continue using it. Downtime or errors can drive them to competitors.

• Supports Business Reputation: A well-functioning system reflects positively on a company’s credibility. Poor availability can damage brand trust.

• Reduces Support Issues: Fewer technical problems mean fewer user complaints. This lowers the burden on customer support teams.

The Formula for Running Availability Tests

There are two parameters used in availability testing in performance testing:

1. Mean Time Between Failure (MTBF)

   The mean time between failures (MTBF) measures how long a system, software, or hardware can be expected to run without failing. This is usually expressed in hours or years.

   To calculate the MTBF, you need to know two things:

   1. The total number of failures that have occurred over a period of time

   2. The total amount of time that has elapsed during that same period

      For example, let’s say that a system has had 10 failures in the last 100 hours. The MTBF would be:

      MTBF = 100 hours / 10 failures

      MTBF = 10 hours

      This means that, on average, the system can be expected to run for 10 hours without fail.

2. Mean Time To Recovery (MTTR)

   MTTR measures the average time to recover from an incident and return to normal functioning. To calculate MTTR, simply add up the total downtime for all incidents over a period of time and then divide by the number of incidents.

   For example, if your software application had three incidents in one week, each lasting for two hours, the total downtime would be six hours. Dividing six by three gives you an MTTR of two hours.

   To calculate availability, you need to know both the MTBF and the MTTR. The formula for availability is:

   Availability = MTBF / (MTBF + MTTR)

   For example, if a system has an MTBF of 100 hours and an MTTR of 10 hours, the availability would be:

   Availability = 100 / (100 + 10)

   Availability = 0.91 or 91%

   This means that the system is available 91% of the time.

How To Run an Availability Test

These are the steps to run an availability test:

1. Design a Test

   To design an availability test, you must first identify your system’s requirements. What resources does it need to function? How many users can it support? Once you have answered these questions, you can start to design your test.

   You can use tools that allow you to simulate the load on a system. It can generate a large number of requests, which will allow you to see how your system responds under high load. As such, you can identify any bottlenecks in your system and make changes to improve its performance.

2. Configure Server Down Manually

   After designing your test, you can run it by manually setting one of your servers down. This way, you can check if your software can handle the loss of a server. You’ll see errors and how your software responds to them.

   Additionally, this should also show you how long it takes for your software to move to the backup node. If you don’t have a second server to use as a backup, you can use virtualization software to create a test environment that mimics your production environment.

3. Check Errors

   The most important thing when running an availability test is to check for errors. You can do this by looking at the software’s logs or by using a monitoring tool. Checking for errors can give you insights into whether the software is stable or not. It should also help you identify any potential issues that need to be fixed.

4. Repeat the Process

   Go through the steps again. This time, make the switch from the backup to the primary server. You can also re-run the process periodically to ensure your software is up-to-date and can handle the latest load.

How does Availability Testing Differ from Other Types of Testing

What are the Latest Trends in Availability Testing?

As software systems become more complex, ensuring their continuous availability is paramount. Recent trends in availability testing reflect advancements in technology and evolving industry practices.

• AI and Machine Learning: AI-driven technologies analyze historical data to forecast potential system failures, allowing proactive measures to enhance system reliability. AI-driven tools can also automate the creation of test cases and adapt to changing system behaviors.

• Shift-left Testing: It emphasizes conducting availability tests early in the software development lifecycle. Organizations can reduce the risk of system downtimes post-deployment by identifying and addressing potential availability issues during the initial stages of development.

• Continuous Testing in DevOps: It ensures that availability is consistently evaluated throughout the development and deployment processes. Automated tests run in integration pipelines can detect availability issues promptly, facilitating immediate remediation and maintaining system uptime.

• IoT System Testing: The proliferation of IoT devices introduces new challenges in availability testing due to these systems' diverse and distributed nature. Consistent availability requires rigorous device interoperability testing, network stability, and real-time data processing capabilities.

• Security-focused Testing: With the increasing prevalence of cyber threats, integrating security considerations into availability testing has become essential. Security vulnerabilities can lead to system outages; thus, testing now includes assessments of how security breaches might impact system availability.

• Generative AI for Test Case Generation: Generative AI is being utilized to create diverse and comprehensive test scenarios, enhancing the robustness of availability testing. AI systems can simulate various operational conditions, identifying potential points of failure that manual testing might overlook.

Conclusion

The primary benefits of high-availability testing are to ensure that the application is always available when needed and to minimize the impact of unplanned outages. By testing the ability of a system to remain operational under normal and adverse conditions, potential issues can be identified and fixed before they cause an unexpected interruption.

If you need help with this process, QASource can provide expert guidance and support. Our team has experience with various testing tools and can work with you to select the right ones for your needs. We also offer comprehensive software and QA testing services, which can be customized to include availability testing as part of a larger project. Contact us for more information and pricing details!