Why Ctime is a Better Indicator

Oct 13, 2025 by wbrum.org 59 views

Introduction

As a user of Navidrome, a music streaming server, you may have encountered issues with the quick scan feature ignoring changes to library modifications. This article aims to provide a detailed explanation of the problem, its expected behavior, and potential solutions.

Problem Statement

When scanning an rsync'd library with modification times preserved, Navidrome exhibits problematic behaviors. Specifically, track additions in folders are ignored if the scan happens in the middle of a transfer, since the folder mtime doesn't change. This issue arises from the fact that Navidrome relies solely on modification times (mtime) to determine changes in the library.

Expected Behavior

The expected behavior is for Navidrome to take into account any folder/file additions, regardless of the modification time. This can be achieved by looking up the creation time (ctime) rather than mtime when scanning. Ctime is a superset of mtime and cannot be altered manually by users or applications, making it a "true" representation of when a file or its metadata is written to disk by the filesystem.

Why Ctime is a Better Indicator

Ctime is a more reliable indicator of file changes because it is not affected by manual modifications, such as chmod and other operations that change ctime but not mtime. By using ctime, Navidrome can accurately detect changes to the library, even if the modification time remains the same.

Potential Solution: Config Option for Ctime Scanning

To address this issue, a config option could be introduced to allow users to choose between mtime and ctime scanning. This option would come with a caveat, warning users that ctime scanning might make search slower in case other applications mess with file metadata.

Benefits of Ctime Scanning

Using ctime scanning would provide several benefits, including:

Improved accuracy: Ctime scanning would ensure that Navidrome accurately detects changes to the library, even if the modification time remains the same.
Reduced false negatives: By using ctime, Navidrome would reduce the likelihood of false negatives, where changes to the library are not detected due to unchanged modification times.
Enhanced user experience: Ctime scanning would provide users with a more accurate and reliable experience, reducing frustration and improving overall satisfaction with Navidrome.

Conclusion

In conclusion, the quick scan feature in Navidrome ignores ctime as an indicator of library modifications, leading to problematic behaviors. By introducing a config option for ctime scanning, Navidrome can improve accuracy, reduce false negatives, and enhance the user experience. We hope that this article has provided a clear understanding of the issue and potential solutions, and we look forward to seeing improvements in future versions of Navidrome.

Additional Information

I confirm that:

[x] I have searched the existing open AND closed issues to see if an issue already exists for the bug I've encountered
[x] I'm using the latest version (your issue may have been fixed already)

Version

v0.55.0

Current Behavior

Scanning an rsync'd library with modification times preserved leads to problematic behaviors (track additions in folders being ignored if the scan happens in the middle of a transfer, since the folder mtime doesn't change, ...).

Expected Behavior

Any folder/file addition should be taken into account. This is possible by looking up the ctime rather than mtime when scanning, as ctime is a superset of mtime and cannot be altered manually by user or application. (it is a "true" representation of when a file or its metadata is written to disk by the filesystem.)

As such, maybe a config option to check ctime rather than mtime during scanning should be available, showing the caveat it might make search slower in case other applications mess with file metadata (e.g. chmod and other such operations change ctime but not mtime, etc).

Steps To Reproduce

No response

Environment

- OS:
- Browser:
- Client:

How Navidrome is installed?

Docker

Configuration

Relevant log output

Anything else?

No response

Code of Conduct

[x] I agree to follow Navidrome's Code of Conduct
[Bug]: Quick Scan Ignores Ctime as an Indicator of Library Modifications ================================================================================

Q&A: Frequently Asked Questions

Q: What is the current behavior of Navidrome's quick scan feature? A: The current behavior of Navidrome's quick scan feature is to ignore changes to library modifications when scanning an rsync'd library with modification times preserved. This leads to problematic behaviors, such as track additions in folders being ignored if the scan happens in the middle of a transfer.

Q: Why is ctime a better indicator of file changes than mtime? A: Ctime is a better indicator of file changes than mtime because it is not affected by manual modifications, such as chmod and other operations that change ctime but not mtime. Ctime is a "true" representation of when a file or its metadata is written to disk by the filesystem.

Q: What are the benefits of using ctime scanning in Navidrome? A: The benefits of using ctime scanning in Navidrome include:

Improved accuracy: Ctime scanning would ensure that Navidrome accurately detects changes to the library, even if the modification time remains the same.
Reduced false negatives: By using ctime, Navidrome would reduce the likelihood of false negatives, where changes to the library are not detected due to unchanged modification times.
Enhanced user experience: Ctime scanning would provide users with a more accurate and reliable experience, reducing frustration and improving overall satisfaction with Navidrome.

Q: How would a config option for ctime scanning work? A: A config option for ctime scanning would allow users to choose between mtime and ctime scanning. This option would come with a caveat, warning users that ctime scanning might make search slower in case other applications mess with file metadata.

Q: What are the potential drawbacks of using ctime scanning in Navidrome? A: The potential drawbacks of using ctime scanning in Navidrome include:

Slower search times: Ctime scanning might make search slower in case other applications mess with file metadata.
Increased complexity: Introducing a config option for ctime scanning would add complexity to the Navidrome configuration.

Q: How can I help resolve this issue? A: You can help resolve this issue by:

Reporting the issue: If you are experiencing this issue, please report it to the Navidrome team.
Providing feedback: Share your thoughts and feedback on the issue to help the Navidrome team understand the impact and prioritize the fix.
Contributing to the solution: If you have the necessary skills and expertise, consider contributing to the solution by helping to implement the fix.

Q: Is this issue already fixed in a later version of Navidrome? A: No, this issue is still present in the latest version of Navidrome (v0.55.0). However, the Navidrome team may have already fixed the issue in a later version. Please check the Navidrome changelog to confirm.

Q: How can I stay up-to-date with the latest developments on this issue? A: You can stay up-to-date with the latest developments on this issue by:

Following the Navidrome GitHub repository: Keep an eye on the Navidrome GitHub repository for updates on the issue.
Subscribing to the Navidrome newsletter: Stay informed about the latest news and updates from the Navidrome team.
Joining the Navidrome community: Participate in the Navidrome community to stay informed and provide feedback on the issue.