Fixing Rez Location Mismatch On Windows Network Drives

by Alex Johnson 55 views

Are you encountering the frustrating location mismatch error when using Rez with mounted network drives on Windows? This issue, similar to the one reported in this GitHub pull request, can halt your workflow and leave you searching for solutions. In this article, we'll dive into the problem, understand why it occurs, and explore potential workarounds to get you back on track. Understanding the root cause and applying the appropriate fixes ensures smooth sailing with Rez, even when dealing with network drives.

Understanding the Rez Location Mismatch Error

Let's break down the error message and what it signifies. The error typically looks like this:

rez.exceptions.ResourceError: location mismatch - requested 'n:\\network\\rez\\os-windows-10.0.19045\\packages', repository location is '\\\\mount-location\\software\\rez\\os-windows-10.0.19045\\packages'

This error arises when Rez tries to resolve packages located on a network drive. The core issue is that Rez is comparing two different representations of the same network path. One representation might be the mapped drive letter (e.g., N:\), while the other is the Universal Naming Convention (UNC) path (e.g., \\mount-location\software\rez). When these paths don't match exactly, Rez throws a ResourceError, preventing it from correctly identifying and utilizing the packages.

The is_local property in Rez checks if a resolved package is located on a local path. When network drives are involved, this check can fail due to the path mismatch. The error occurs during the resolution process when Rez attempts to determine the package's location, and it cannot reconcile the requested path with the repository's actual location. This is especially common in environments where network drives are mapped differently across various machines or sessions. Ensuring consistent path resolution is critical for Rez to function correctly with network resources. Understanding this mismatch is the first step towards finding a viable workaround and resolving the issue.

Why This Happens: A Deeper Dive

The underlying reason for this issue lies in how Windows handles network paths and how Rez interprets them. Windows allows accessing network shares via mapped drive letters or UNC paths. While both methods point to the same location, they are treated as distinct paths by the operating system. Rez, in its attempt to locate package resources, may encounter a situation where it expects one path format but receives another, leading to the mismatch error.

Moreover, the history of fixes and rollbacks, as mentioned in the original issue, highlights the complexity of this problem. The initial fix using canonical_path aimed to normalize the paths but was later reverted. This suggests that while canonical_path might have addressed the issue in some cases, it likely introduced other problems or inconsistencies. The rollback indicates the need for a more robust and comprehensive solution that handles various network configurations and path representations correctly. Therefore, understanding the nuances of Windows path handling and Rez's path resolution mechanism is crucial for identifying the most effective workaround. In essence, the challenge is to ensure that Rez consistently interprets network paths, regardless of whether they are represented as drive letters or UNC paths.

Potential Workarounds for the Location Mismatch Error

While a definitive fix might require changes to Rez itself, several workarounds can help you mitigate this issue in the meantime. Here are some strategies you can try:

  1. Use UNC Paths Consistently: Ensure that all your Rez configurations and environment variables use UNC paths instead of mapped drive letters. This means replacing paths like N:\software\rez with \\mount-location\software\rez. This approach promotes consistency and eliminates the ambiguity caused by different path representations. Modifying your Rez configuration files and environment variables to use UNC paths can significantly reduce the likelihood of encountering the location mismatch error.

  2. Modify the rezconfig.py File: You can try modifying the rezconfig.py file to force Rez to use UNC paths. Locate the configuration settings related to package paths and update them to use UNC paths explicitly. This might involve adding or modifying variables like packages_path or plugin_path to ensure they point to the correct network locations using UNC paths. Be cautious when modifying configuration files and always back up the original file before making any changes. Incorrect modifications can lead to other issues, so it's important to proceed with care and test thoroughly after making any changes.

  3. Create a Symbolic Link: Create a symbolic link that maps the drive letter to the UNC path. This can be done using the mklink command in Windows. For example:

mklink /D N:\ \mount-location\software\rez ```

This creates a symbolic link that makes the drive letter `N:` point directly to the UNC path. This can help Rez resolve the path correctly by providing a consistent mapping between the drive letter and the UNC path. Symbolic links can be a powerful tool for managing paths and ensuring consistency across different systems. However, be aware that symbolic links can sometimes introduce other issues, so it's important to test thoroughly after creating them.

  1. Environment Variables: Use environment variables to define your Rez package paths, and ensure these variables use UNC paths. This can provide a level of abstraction and make it easier to manage paths across different systems. For example, you can define an environment variable called REZ_PACKAGES_PATH and set it to the UNC path of your Rez packages directory. Then, in your Rez configuration files, you can refer to this environment variable instead of hardcoding the path. This approach makes it easier to update the path if it changes in the future, and it also ensures that all systems are using the same path representation.

  2. Update Rez (If Possible): Keep your Rez installation up to date. While the specific fix mentioned earlier was rolled back, newer versions of Rez might include improvements or bug fixes that address this issue. Check the Rez changelog and release notes to see if there are any relevant updates that could resolve the location mismatch error. Updating Rez is generally a good practice, as it ensures you have the latest features and bug fixes.

  3. Report the Issue: If none of the above workarounds resolve the issue, consider reporting it to the Rez developers. Provide detailed information about your setup, including your operating system, Rez version, network configuration, and the steps you've taken to try to resolve the issue. The more information you provide, the better the developers will be able to understand the problem and develop a solution. Reporting the issue can also help other users who are experiencing the same problem.

  4. Test with a Simplified Setup: Try to reproduce the issue with a simplified Rez setup. This can help you isolate the problem and determine whether it's related to your specific configuration or a more general issue with Rez and network drives. For example, you can create a minimal Rez package and try to resolve it on a test machine with a network drive. If you can reproduce the issue with a simplified setup, it's more likely that it's a general problem with Rez and network drives.

Conclusion

Dealing with location mismatch errors in Rez when using mounted network drives on Windows can be a challenge. However, by understanding the root cause and applying the workarounds discussed in this article, you can mitigate the issue and keep your Rez-based workflow running smoothly. Remember to use UNC paths consistently, consider modifying the rezconfig.py file, and explore the use of symbolic links and environment variables. By implementing these strategies, you can overcome the location mismatch error and leverage the power of Rez in your production environment.

For more in-depth information about Rez and its configuration, refer to the official Rez documentation on the Read the Docs website.