Responsibilities of the SCSI Device Driver

The SCSI device driver (the upper layer) provides the rest of the operating system with the software interface to a given SCSI device or device class. The upper layer recognizes which SCSI commands are required to control a particular SCSI device or device class.

The SCSI device driver builds I/O requests containing device SCSI commands and sends them to the SCSI adapter device driver in the sequence needed to operate the device successfully. The SCSI device driver cannot manage adapter resources or give the SCSI command to the adapter. Specifics about the adapter and system hardware are left to the lower layer.

The SCSI device driver also provides recovery and logging for errors related to the SCSI device it controls.

The operating system provides several kernel services allowing the SCSI device driver to communicate with SCSI adapter device driver entry points without having the actual name or address of those entry points. The description contained in Logical File System Kernel Services can provide more information.