If you are using the Vagrant VirtualBox provider, then VirtualBox shared folders are the default synced folder type. These synced folders use the VirtualBox shared folder system to sync file changes from the guest to the host and vice versa.
SharedFoldersEnableSymlinksCreate(boolean) - If false, will disable the ability to create symlinks with the given virtualbox shared folder. Defaults to true if the option is not present.
There is a VirtualBox bug related to
sendfile which can result
in corrupted or non-updating files. You should deactivate
sendfile in any
web servers you may be running.