3.2.2. Installation drives

The Firebird server — and any databases you create or connect to — must reside on a hard drive that is physically connected to the host machine. You cannot locate components of the server, or any database, on a mapped drive, a filesystem share or a network filesystem. (Well, you can, but you shouldn’t, and this technique isn’t covered here.)

You can mount a read-only database on a CD-ROM drive, but you cannot run Firebird server from one.