The OS2DASD Device Manager (OS2DASD.DMD) provides the interface between the OS/2 File Systems (FAT, HPFS) and Adapter Drivers (*.ADDs) that support fixed and removable magnetic disks.

This device manager allows the *.ADD drivers to communicate with adapter or disk hardware without interacting with the logical contents of these devices or being affected by the complexity of OS/2 block device driver interfaces. The device manager communicates with *.ADD drivers exclusively by way of Input/Output Request Blocks (IORBs), as described in the preceding chapters of the Storage Device Driver Reference.

The primary functions of this device manager are:

• Implementing the OS/2 Kernel/FileSystem block device driver interfaces; creating IORBs as required for communication to .ADD drivers.

• Scanning .ADD drivers for removable or fixed magnetic devices.

• Managing partitioned devices by creating logical drives for partitioned disks and reporting these logical drives to the OS/2 kernel.

• Providing IOCtl interfaces to the file system utility applications to allow for the preparation of the media.

• Providing for the attachment from a set of logical drives to a physical removable device is called pseudo drive support. An example is the mapping of drive A: or B: to a single diskette drive.