The data is stored in raw partitions. initially wa had a Unix server but since none in our staff is hendy with unix we decided to move the database to Windows NT. It supports file and raw partitions just as Unix does and it has been absolutly stable, no problems.
By the way the kind of filesystem or even Informix platform is meaningless to Delphi since it connects with the server by an IP port no matter if it is Unix or NT or raw or file.
Ok let see: in hostname you use the machine's name, or better yet for W2k and above, the IP adress of the host that runs Informix.
Serverneme is the name of your Informix instance, check DBSERVERNAME parameter on the onconfig file. Servicename is the name of the listening service that will process the client's request it's configured at server's installation, it could be Turbo at 1526 port, check the services file or setnet config at your host. I alse recommend you that use the port number and not the name in W2000 and above.
Protocol could be onsoctcp or olsoctcp, check NETTYPE at the onconfig file.