DASD device driver
The DASD device driver provides access to all real or emulated direct access storage devices (DASD) that can be attached to the channel subsystem of an IBM® mainframe.
DASD devices include various physical media on which data is organized in blocks or records or both. The blocks or records in a DASD can be accessed for read or write in random order.
Traditional DASD devices are attached to a control unit that is connected to a mainframe I/O channel. Today, these real DASDs have been largely replaced by emulated DASDs. For example, emulated DASDs can be the volumes of the IBM System Storage® DS8000® Turbo, or the volumes of the IBM System Storage DS6000™. These emulated DASD are completely virtual and the identity of the physical device is hidden.
SCSI disks that are attached through an FCP channel are not classified as DASD. They are handled by the zfcp driver.