I am in the process of building a Vagrant external link Box for work external link . All was going great until I ended up having to spend the best part of two days trying to figure out why static files (css, javascript etc) were not being served after being updated on the host file system.

Turns out that VirtualBox external link has had a “bug” for around three years where if “sendfile external link ” is enabled in the web server you are running it won’t serve a file after it has been changed on the file system mounted from the host machine.

This function, a kernel call to copy files directly from disc to TCP, is used by both NGINX & Apache to help serve static content more efficiently.

The issue is documented here ….

…. hopefully this post will save anyone messing about ETAGS external link , NFS external link or caching settings within their web server or applications for hours.

Also, it was a good lesson in Google early (hence the Picard faceplam) !!!