I live in Germany, so I use the funny European diacritical marks a lot :-)
This was no problem, as long as I used only Ubuntu server and Ubuntu clients in my network. And even when I moved all the files from the Ubuntu server to my new MyBook NSA appliance I could mount all the directories via nfs and everything would look fine. Apparently the files were copied to the MyBook as they should. It seems the file names were transferred as they were, having the characters encoded in UTF-8, the default with Ubuntu.
Now that I installed the MediaTomb UPnP server on the MyBook, I realized that the file names on the MyBook are not interpreted as they should. This is a problem, because the MediaTomb server cuts the names of the media files after it discovers a non-display character. Besides, it would be nice to see the names correctly.
What do I need to set, to make this work? Change codepage or charset mappings inside the /etc/fstab file? Install and set a German locale? Something else? I hope one of you have a hint for me.
Ah yes, btw, I use the Optware way to install/update software on the MyBook.
OK, I didn't solve the problem with the locale. But by doing some fine-tuning of the config.xml file, the names are fine now in MediaTomb. For now this is enough for me, therefore I consider this thread as solved.