What is Stress Testing?

Stress testing (or load testing) in software design is a type of performance testing that evaluates how a system behaves under extreme or unfavorable conditions. The goal is to determine the system’s stability, reliability, and robustness when pushed beyond normal operational limits.

What Stress Testing Involves

This process goes beyond normal performance checks. Instead, stress testing is designed to push systems to their limits to uncover weaknesses that only appear under extreme conditions.  Here’s how it’s accomplished;

• Simulating high load: Applying workloads much higher than expected (e.g., thousands of concurrent users)
• Resource exhaustion: Testing scenarios where memory, CPU, disk space, or network bandwidth are heavily consumed
• Failure conditions: Introducing conditions like database unavailability, slow network, or hardware failures

Why Stress Test?

By simulating worst-case scenarios, stress testing ensures your infrastructure can withstand unexpected spikes, resource strain, and critical failures without compromising stability or security. Specifically, it can:

• Identify bottlenecks and weak points
• Ensure the system fails gracefully rather than crashing abruptly
• Validate recovery mechanisms (e.g., auto-scaling, failover systems)

Key Metrics for Stress Testing

System resilience is more than just surviving heavy loads. Resilience also demonstrates how well your application performs under pressure. The following metrics reveal whether your infrastructure can handle stress and recover quickly without compromising user experience.

• Response time under stress.
• Error rates and system crashes.
• Recovery time after overload.

Stress Testing Managed File Transfer (MFT)

Stress testing in Managed File Transfer (MFT) refers to evaluating the system’s ability to handle extreme workloads and adverse conditions when transferring files between systems. The goal is to ensure that the MFT solution remains stable, secure, and reliable under stress scenarios.

MFT systems often handle mission-critical and sensitive data such as financial transactions, healthcare records, supply chain files, etc. Stress testing helps ensure there is no data loss, critical data is delivered on time, and that the system is resilient during peak periods, such as end-of-month processing or seasonal spikes.

It’s All About the Hardware

The operation of performing a file transfer on a computer engages almost every component of a computing architecture, CPU, memory, system bus (data transport system on a mother board of a computer) and network card.  In short, CPU is used for processing the encryption and compression, RAM is used for buffering, NIC (Network Interface Card) is used for network throughput and disk for read/write file system operations. Only the graphics card and floating-point arithmetic are not utilized during file transfers. Under the high loads, the speed of the bus is particularly important.

The performance of the MFT server is directly related to the performance of the hardware used for deployment. Stress testing MFT essentially stress tests almost the entirety of the computing architecture.

Stay Away from Bursting! Or Understand How It Affects MFT Workflows.

Many cloud computing vendors (such as AWS or Windows Azure) offer or almost force their users to use bursting. Cloud bursting is a cloud configuration method that allows applications to run in a private cloud or data center and “burst” into a public cloud when computing demand spikes. Cloud bursting provides a way for organizations to handle sudden increases in workload without having to maintain excess capacity in their own infrastructure.

However, even if bursting sounds like a good idea in theory, in practice with file transfer applications, bursting provides a skewed view of the file transfer performance.  Under most cloud deployments, computing systems come with a certain amount of “bursting credits” and once the bursting credit is finished, the system falls back to the baseline performance. In the first 30 minutes, this usually looks like the file transfer speed is great, until suddenly, the file transfer speed (or throughput) drops to a much lower baseline speed.

MFT stress testing is a very good method to discover how the bursting time limits affect your daily file transfer workflows and how to work around it. 

It’s Also All About the Network

During file transfer, several parts of the network infrastructure are heavily utilized. Here’s a detailed breakdown:

1. Network Interface Cards (NICs)

• NICs are found on both the sending and receiving systems.
• They handle packet transmission and reception.
• High-speed NICs (1Gbps, 10Gbps, or higher) are critical for large transfers.

2. Switches

• Switches forward packets between devices within the same network.
• Switch backplane capacity and port speed matter for high-volume transfers.
• QoS (Quality of Service) settings can affect performance under load.

3. Routers

• Routers direct traffic between different networks or subnets.
• Routing tables and CPU performance impact throughput.
• NAT and firewall rules can add processing overhead.

4. Firewalls

• Firewalls are vital to inspect packets for security.
• Stateful inspection and deep packet analysis can slow transfers, if not optimized.
• Hardware firewalls with dedicated ASICs or Applications-Specific Integrated Circuits handle heavy loads better.

5. Wide Area Network (WAN) Links / Internet Backbone

• If the transfer is across a public internet, bandwidth and latency are key.
• Congestion or packet loss on WAN links can severely impact performance of many file transfer protocols, including but not limited to, SFTP, FTPS, and HTTP.

6. Load Balancers (if used)

• The balancers distribute traffic across multiple servers.

• Load balancing is Important in high-availability MFT setups.

  Related Reading: High Availability: What’s the Risk of Not Having It?
   

7. VPN Gateways (if applicable)

• Encrypt and tunnel traffic
• Adds CPU overhead and latency
• VPNs are usually not designed to sustain long-term high throughput of a file transfer and are responsible for many bottlenecks during a file transfer session.

8. Web Application Firewall WAF (if used)

• Verifies the syntax and validity of all incoming HTTP requests
• Throttles or blocks repetitive HTTP requests that can potentially cause a denial of service (DoS) attack
• File transfers via HTTP require very long running HTTP requests or sometimes can be broken into thousands of smaller HTTP requests; some WAFs could categorize long running HTTP upload/download (PUT/POST/GET) requests as malicious and to start randomly block legitimate file transfers.

Related Reading: WAFS Add Layer of Security When Using Web-Based Apps

Stress testing your MFT solution will push your entire network infrastructure to the limit. We recommend that any MFT stress test is performed in collaboration with your network team so they can actively monitor the network infrastructure during testing.

Types of Stress Testing

There are two types of stress testing: destructive and non-destructive.  Let’s review what each type means within the context of MFT.

Destructive Stress Testing

In this type of stress testing, we will apply extreme server load to bring the MFT server into a failure state. With destructive stress testing, our goal is to see how the MFT server will react during the extreme loads with hundreds or even thousands of concurrent file transfers.  This type of testing cannot be performed on production systems as it will affect your MFT service delivery.

In the case of Continuous Deployment or Continuous Delivery (CI/CD), destructive stress testing has to be well designed and safely integrated into the rest of the production deployment workflow.

Non-destructive Stress Testing

Under non-destructive stress testing methods, one could look for performance of individual file transfer sessions. For example, we could look for how huge files are handled by the MFT solution. Huge files could mean a different thing to everyone. For some organizations, a huge file could be 1-2GB, for others, that size is 100-200GB, and finally for some enterprises, a huge file could be 1-2TB.

Another non-destructive type of stress testing could be testing extreme network conditions where latency and packet loss on the network are purposely set to very high to observe the performance of the file transfer.  For example, someone could start a test from a computer very far away from the MFT deployment and see how the file transfer behaves. Some file transfer protocols are better at long distance transfers than others. For example, FTPS will behave better than SFTP in high latency.  There are also specialized, UDP-based file transfer acceleration protocols that promise to work around high latency and high packet loss connections.

Another type of non-destructive testing could be high network instability, meaning that during a transfer the client must reconnect, retry, and resume a file transfer multiple times. In this case, one would watch for any data corruption in the transferred files.  Some kind of independent verification mechanism must be built to verify (either via MD5 or SHA) the data integrity of a file after transfer.

Stress Testing: A Must for Ensuring Security and Deliverability

If your MFT system handles mission-critical data for your business or you are thinking of migrating to the cloud or to a new hardware, having stress test result data for your current MFT solution in hand will make your team much more educated about making the next strategic decision regarding your MFT system. 

MFT stress testing will also teach you a lot about your hardware and network infrastructure and what your organization is ready to handle.  Non-destructive stress testing will let you explore the file size limits and longest distances your MFT service can support. Undertaking these exercises is time well spent when it comes to ensuring the security and deliverability of your most sensitive and critical data.

Watch for Part 2 of our stress test series in January 2026. We’ll dive deeper into GoAnywhere MFT specifics, concentrating on methodology and tools used at Fortra MFT to stress test GoAnywhere. We will also explain how we produce our benchmark results and introduce the stress test services offered by our Fortra MFT Professional Services team.