A Guide to Availability Testing for Software

Timothy Joseph
Timothy Joseph | January 24, 2023

A Guide to Availability Testing for Software

Today's modern applications are dependent on a variety of 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 great 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 to solve this problem. Whether you’re developing a new application or trying to improve the performance of an existing one, availability testing is an important part of the process. You need to know how your software will perform under different conditions and in different 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 a type of performance testing that is conducted to check whether a system is able to meet the required availability SLA (service-level agreement). The purpose of this testing is 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.

These are the types of availability testing:

  1. Ping Testing of URL

    This is a type of availability testing that 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 from it. If we don’t get a reply from the server, it means that either the server is down or there is some problem with network connectivity.

  2. Multi-step Web Test

    A multi-step web test is a type of availability testing in software testing that simulates real user traffic patterns in order 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 one follows a defined scenario, such as buying a product on an eCommerce site.

    The goal of multi-step web tests is 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.

  3. Standard Test

    A standard test is used to determine the percentage of time that a system or application is available for use. It does not take into account 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 that the system or application is available for use, divided by the total time period being considered.

  4. 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.


Why Is Availability Testing Important?

It’s important to test for availability because downtime can have a significant impact on 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.


How Does It Impact User Experience?

The goal of availability testing is to ensure that a software system can continue to function 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.

This can lead to frustration, and in some cases, loss of business. For example, if an eCommerce site is unavailable during a peak sales period, the company may lose out on a significant amount of revenue.


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 failure (MTBF) is a measure of 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 it takes 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 first need to identify what your system’s requirements are. What resources does it need in order 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 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 setting one of your servers down manually. This way, you can check if your software is able to 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 that your software is up-to-date and able to handle the latest load.


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 then use to compare different software systems.

  • Automated Test Cases

    One of the features of availability testing is that it can be automated. This means that you can create test cases and then have them run automatically. This can save you a lot of time and effort, as well as 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.



The primary benefits of high-availability testing are to ensure that software 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 a wide variety of available testing tools and can work with you to select the right ones for your needs. We also offer comprehensive software testing services, which can be customized to include availability testing as part of a larger project. Contact us for more information and pricing details!


This publication is for informational purposes only, and nothing contained in it should be considered legal advice. We expressly disclaim any warranty or responsibility for damages arising out of this information and encourage you to consult with legal counsel regarding your specific needs. We do not undertake any duty to update previously posted materials.