GitHub Actions: Fix Virtual Drive Load Failures (>2GB)

Aug 6, 2025 by Viktoria Ivanova 55 views

Troubleshooting GitHub Actions: Builds Failing to Load Virtual Hard Drives Larger Than 2GB

Hey everyone! Are you encountering issues with your GitHub Actions builds failing when loading virtual hard drives larger than 2GB? You're not alone! This article dives deep into a peculiar problem encountered specifically in GitHub Actions builds when dealing with virtual hard drives exceeding the 2GB limit. Let's explore the issue, understand the possible causes, and discuss potential solutions. If you're wrestling with this, stick around – we're here to help!

The Issue: GitHub Actions and Large Virtual Hard Drives

So, what's the deal? The core problem is that GitHub Actions builds seem to have trouble loading virtual hard drive images, especially those in raw or VHD format, when they're bigger than 2GB. Imagine you're trying to set up a retro gaming environment using DOSBox-Pure within your CI/CD pipeline. You've got your main drive for the operating system (like Windows 98) and an additional drive loaded with games. Normally, this works like a charm. But when you try to load a virtual drive larger than 2GB in your GitHub Actions build, things go south.

The error message you might encounter is something like "Unable to open CD-ROM image file." This is misleading because you're not actually dealing with a CD-ROM image; you're trying to mount a fixed block drive. It seems the system might be incorrectly assuming these larger drives are CD images, leading to the failure. Interestingly, the preview2 version doesn't seem to have this issue, which adds another layer to the mystery. This issue highlights a significant roadblock for anyone relying on GitHub Actions for automated testing or building of systems that require larger virtual hard drive images. Getting to the bottom of this is crucial for streamlining workflows and ensuring consistent build processes. Understanding the root cause will not only solve the immediate problem but also prevent future headaches.

Diving Deeper: Symptoms and Observations

To really nail down the problem, let's look at the specific symptoms and observations. One key symptom is that the frontend throws an error when attempting to load raw or VHD files that are even slightly larger than 2GB. For instance, a 2048MB drive might work fine, but a 2052MB drive will cause the build to fail. This is a critical detail, suggesting the issue isn't just about sheer size but something specifically triggered when crossing that 2GB threshold. It's almost like a gatekeeper, silently blocking anything that exceeds its limit. Another important observation is how the system behaves when you try to interact with the virtual drive through the command line. If you regularly mount a system folder using command-line tools and then run a directory listing (DIR), the drive only shows up if it's 2GB or smaller. This reinforces the idea that the system has a hard time recognizing and handling larger drives. Think of it as the system turning a blind eye to anything beyond its comfort zone. This consistent behavior across different methods of accessing the drive points towards a fundamental limitation or bug within the GitHub Actions environment.

For example, consider the following scenario:

# Creating a 2048MB virtual drive (works fine)
imgmake -t hd test.img -size 2048 -fat 32

# Creating a 2052MB virtual drive (fails)
imgmake -t hd test.img -size 2052 -fat 32

These commands highlight the stark contrast in behavior. The imgmake command, used in DOSBox-X to create virtual drive images, perfectly illustrates the issue. When you create a drive with a size of 2048MB, everything goes smoothly. But bump that size up just a little bit – to 2052MB – and suddenly, you're facing build failures. This precise point of failure is incredibly valuable for debugging and narrowing down the potential causes. It suggests that there's some kind of size check or allocation limit within the GitHub Actions environment that's being triggered by these slightly larger drives. This kind of detail is what separates a general problem report from a focused investigation, paving the way for a more targeted solution.

Possible Causes and Theories

So, what could be causing this? Let's put on our detective hats and explore some theories. One potential cause is that the underlying virtualization environment in GitHub Actions might have limitations on the size of virtual drives it can handle. It's possible that there's a hard-coded limit or a configuration issue that restricts the maximum size to 2GB. This kind of limitation could stem from the specific virtualization technology used by GitHub Actions or how it's configured. Another theory revolves around how the system interprets the drive image format. As mentioned earlier, the error message "Unable to open CD-ROM image file" suggests that the system might be misidentifying larger drives as CD-ROM images, which would explain why it fails to load them correctly. This misidentification could be due to a bug in the drive detection logic or a missing driver or component needed to handle larger virtual drives. Think of it like trying to fit a square peg in a round hole – the system is trying to interpret the drive in the wrong way, leading to a failure.

Another factor to consider is the file system within the virtual drive. The example uses FAT32, which has its own limitations and quirks. While FAT32 can technically support drives larger than 2GB, there might be specific edge cases or compatibility issues within the GitHub Actions environment that are triggered by larger FAT32 volumes. It's possible that the way the virtual drive is formatted or partitioned interacts with the virtualization layer in unexpected ways, leading to the loading failures. Moreover, resource constraints within the GitHub Actions environment could also play a role. Running a build involves allocating CPU, memory, and disk I/O resources. If there are limitations on these resources, especially when dealing with larger files or drives, it could lead to failures. Perhaps the system runs out of memory or encounters I/O bottlenecks when trying to load a drive larger than 2GB. This would be like trying to pour water into a glass that's already full – the system simply can't handle the load.

Potential Solutions and Workarounds

Okay, enough about the problem – let's talk solutions! If you're facing this issue, there are a few things you can try. While we haven't pinpointed the exact cause yet, here are some potential workarounds and approaches:

Splitting the Drive: One immediate workaround is to split the virtual drive into smaller chunks, each under 2GB. This might involve creating multiple virtual drives and mounting them separately within your environment. It's not ideal, but it can get you moving forward while we dig deeper. Think of it as breaking a large task into smaller, manageable pieces. It might be more cumbersome, but it's often a reliable way to overcome limitations. This method allows you to work around the size restriction by distributing your data across multiple smaller drives, each of which the system can handle without issue. This approach requires careful planning and management of your virtual drives, but it can be a practical solution in the short term.
Exploring Different Image Formats: Another avenue to explore is using different virtual drive image formats. While raw and VHD are common, there might be other formats that GitHub Actions handles more gracefully. For instance, you could try using VMDK or QCOW2 formats, which are often associated with more advanced virtualization platforms. This approach is based on the idea that the system's handling of different image formats might vary, and switching to a different format could bypass the 2GB limitation. It's like trying different keys to see which one fits the lock – experimenting with formats could reveal a compatible option. Before committing to this approach, research the compatibility and performance characteristics of different image formats within the GitHub Actions environment.
Checking for Updates: Always ensure that your tools and dependencies are up to date. There might be bug fixes or improvements in newer versions of DOSBox-Pure or the GitHub Actions runner that address this issue. Keeping your environment current is a best practice in general, and it can often resolve unexpected problems. This is akin to making sure you have the latest version of your software – updates often include fixes for known issues and improvements to performance and compatibility. Regularly updating your tools and dependencies ensures that you're benefiting from the latest advancements and bug fixes, which could potentially resolve the 2GB limitation problem.
Investigating GitHub Actions Environment: Dig into the specifics of the GitHub Actions environment. Are there any documented limitations on virtual drive sizes? Are there specific configurations or settings that might be affecting this? Sometimes, the answer lies in the fine print. This involves delving into the documentation and configuration settings of GitHub Actions to identify any constraints or limitations related to virtual drive sizes. It's like reading the manual to understand the rules of the game – knowing the environment's limitations can help you tailor your approach and avoid potential pitfalls. This investigation might uncover specific settings or configurations that need to be adjusted to accommodate larger virtual drives.

Community and Collaboration: Let's Solve This Together!

The beauty of open-source and platforms like GitHub is the power of community. If you're facing this issue, chances are others are too. Let's collaborate to find a solution! Share your experiences, experiments, and findings in forums, issue trackers, and discussions. By pooling our knowledge, we can collectively troubleshoot and overcome this hurdle. Think of it as a puzzle – each person's contribution adds a piece to the solution. By sharing your insights and experiences, you can help others who are facing the same problem and contribute to a comprehensive understanding of the issue. The more people involved in the discussion, the faster we can identify patterns, test different approaches, and ultimately find a solution.

To further this collaborative effort, consider the following:

Share your GitHub Actions workflow configurations: Posting snippets of your workflow configuration can help others identify potential issues or suggest improvements. It's like sharing your recipe so others can try it and offer feedback. By sharing your configuration, you allow others to examine your setup and identify any areas where the 2GB limitation might be triggered. This transparency can lead to valuable insights and potential solutions.
Document your experiments: If you've tried different workarounds or approaches, document them. What worked? What didn't? This information is invaluable for others who are trying to solve the same problem. Think of it as creating a troubleshooting guide – your experiences can help others avoid dead ends and focus on promising solutions. Documenting your experiments provides a valuable record of your efforts, allowing others to learn from your successes and failures.
Engage in discussions: Participate in relevant forums, issue trackers, and online communities. Share your findings, ask questions, and offer suggestions. This active engagement is crucial for fostering collaboration and driving towards a solution. This active participation can spark new ideas, uncover hidden details, and accelerate the problem-solving process.

By working together, we can conquer this challenge and make GitHub Actions even more powerful for everyone!

Conclusion: Navigating the 2GB Virtual Drive Limit in GitHub Actions

In conclusion, the issue of GitHub Actions builds failing to load virtual hard drives larger than 2GB is a frustrating but solvable problem. We've explored the symptoms, potential causes, and some initial workarounds. While the exact root cause remains elusive, the strategies outlined here – splitting drives, exploring different image formats, checking for updates, and investigating the GitHub Actions environment – provide a solid starting point for troubleshooting. Remember, the power of community is key. By sharing our experiences and working together, we can overcome this limitation and continue to leverage GitHub Actions for our projects. So, let's keep experimenting, keep communicating, and keep pushing the boundaries of what's possible!

If you've encountered this issue or have any insights to share, please jump into the comments below or join the discussions in relevant forums and communities. Your contribution could be the missing piece of the puzzle! Let's make sure that working with larger virtual drives in GitHub Actions becomes a seamless experience for everyone.