Comment 2 for bug 1907138

You answered your own question when you use the command df. No application can magically determine prior to download what the available storage space is when it doesn't know which subfolders precisely the files will be downloaded to. All it can go with is the size of the volume the destination is located in, which 99.9% of the time will be the same volume as its subfolders.

The code in question is found here:

https://github.com/damonlynch/rapid-photo-downloader/blob/main/raphodo/storage.py#L1721

It's using standard system calls. Nothing fancy.

The first thing you need to do is set up your NAS / container so that the actual size of the storage medium used is correctly reported. Download to a destination folder *inside* the actual destination storage medium, not the mount point in which it is residing:

/media * DO NOT CHOOSE THIS *
/media/photo_destination_storage/photos * CHOOSE SOMETHING LIKE THIS *