DVD Multifunction Devices: Avoiding Multiple Logical Unit Devices
Computer manufacturers are offering DVD devices in their platforms at a steeper adoption rate than the incorporation of CD-ROM into the PC platform. Therefore, it is important for hardware and software developers to agree upon and implement common interfaces to ensure consistent customer use and expectations. This common interface needs to be driven from both the side of the hardware interconnect and also from the side of interaction with the operating system and device software support.
Currently, there are many different varieties of CD / DVD and optical storage that can be added into or purchased with PCs.
These include the following, plus others:
CD-ROM | DVD-ROM |
CD-R | DVD-RAM |
CD-RW | MO (Magneto Optical) |
PD (Phase Change Drives) |
Some of these devices share a common interface and command structures, such as the Mt. Fuji specification for DVD and CD devices, and others are implemented on unique command sets.
The implementation of multiple logical units (LUNs) of distinctly different features into one drive forces the operating system to present confusing information to the end user. For example, in Microsoft Windows 98, a drive with PD/MO and DVD/CD functions on separate LUNs appears as two separate drive selections to the customers. As DVD continues to evolve and segment, the production of units with this style of LUN support is not attractive to the end user or to support organizations.
For new devices in the DVD market, Microsoft is strongly evangelizing a single LUN support, implementing common command sets that support all features of the device as one Logical Unit. This support for DVD-ROM and CD devices is currently built into the Windows operating systems, and will be developed for agreed-upon new DVD features and support.
For devices selling now that integrate multiple LUNs, the current support will continue, but expansion of this support is not expected. Therefore, new devices such as DVD-RAM, DVD+RW, or others would be expected to use the single LUN approach. Microsoft sees this as a way to provide an enhanced customer experience and reduce confusion after the sale.
Call to action for DVD multifunction devices:
| • | For Windows 98, Windows NT 4.0, Windows 2000, and Windows XP, use one LUN and supply a class driver in order to provide the best user experience and best feature set. |
