Installable file systems work with a variety of storage devices. A file system on a local device such as a disk drive or virtual drive is called a local file system. A file system on a remote device, such as a disk drive on another computer, is called a remote file system. An application can establish a connection to a local or a remote file system by using DosFSAttach.

For a local file system, the operating system uses a block device driver, which accesses disk hardware, to handle input and output to the device. The operating system automatically connects most (if not all) local file systems when it starts. However, an application can attach and detach additional file systems as needed.

For a remote file system, the operating system uses a device driver that typically accesses a communications or network device. Usually, the actual storage device is located on another computer, and the two computers communicate requests and data through a network connection. An application can associate a remote file system with a drive letter by using DosFSAttach. Once the connection is made, the application can access directories and files on the remote device simply by using the assigned drive letter, treating the remote device as if it were on the same computer.