Here's my use case. I have a raspberry pi 4 running as a jellyfin (https://jellyfin.org/) server to play the movies I have ripped from the DVDs I buy (just so you know this is all legit). I do the same with music I buy from iTunes (yes that still exists, and yes you can still own you music). The media is all stored on an NTFS volume, and of course the pi is running Linux.
Jellyfin has been working really well. It looks up the names of people involved with the creation of the media automatically, and stores it under a directory called "/metadata" on the same NTFS volume. I mirror the metadata directory (and a few others) to my local Windows 11 computer so that it won't have to be completely rebuilt if for some reason there is a problem with the server, which can happen from time to time when there is an OS or software update. The pi has sftp built in, so I use that. The volume on the windows computer is also NTFS.
Under "/metadata" there are numerous directories with a single letter name. All people starting with the letter "A" are stored under a directory called "A", etc. Jellyfin has no problem with names that start with lower case letters, it just creates a directory with a single letter name that is lower case. However, when I try to mirror them to my local NTFS volume, FFS seems to have problems. In this particular case, on the server there are directories:
"d" and "D"
"e" and "E"
"f" and "F"
"m" and "M"
"s" and "S"
"t" and "T"
10:40:35 PM Info Synchronizing folder pair: Custom <>
E:\metadata
sftp://pi@192.168.1.70/media/pi/stuff/metadata
10:40:35 PM Info Deleting folder "E:\metadata\People\D\d'bi.young anitafrika"
10:40:35 PM Info Deleting folder "E:\metadata\People\E\ensemble"
10:40:35 PM Info Deleting folder "E:\metadata\People\F\final fantasy"
10:40:35 PM Info Deleting folder "E:\metadata\People\m\M. Emmet Walsh"
10:40:35 PM Info Deleting folder "E:\metadata\People\m\M. Leona Godin"
FFS of course deletes all the local directories under "m" because on the server they exist under "M", and then it copies over the files from the server that it just wiped out -- and puts them under "m". The result is not a disaster, just not expected behavior, and an unnecessary waste of bandwidth and time. What I end up with is "ensemble" in the "E" directory along with all the names that start with "E" like "Eddie Izzard". Etc.
I eventually figured out that for whatever reason, Windows NTFS won't let you have two names in the same directory that only differ by case. So no "m" and "M". Linux obviously does permit this. Microsoft might see this as incorrect behavior, but to me the Linux way makes more sense.
Sorry if I'm re-hashing old news. This is not a fault in your software. But could you code around this for the windows version when it's writing MS volumes? Maybe using hex encoding? Or some transparent on-the-fly bi-directional translation controlled by a flag?
Maybe this is just too much of a niche case.
FFS has no problem with the directory "แนข", or any other internationally accented characters. I bet it would work for the various non-roman alphabets, or even emoji, as well.
Thank you for your attention to this.