A.3.1 Using the Tape Class Driver

The system-supplied tape class driver implements device-independent, OS-specific tape support and exports support routines to the device-specific tape miniclass drivers.

The tape class driver:

• Performs a large part of miniclass driver initialization, including allocating and initializing OS resources for the miniclass driver and the devices it supports.

• Exports memory allocation and initialization routines.

• Recognizes the maximum transfer size for HBAs and splits transfer requests when necessary.

• Handles IRP_MJ_CREATE, IRP_MJ_READ, and IRP_MJ_WRITE requests.

• Handles IOCTL_TAPE_CHECK_VERIFY, IOCTL_TAPE_FIND_NEW_DEVICES, and IOCTL_TAPE_REMOVE_DEVICE requests.

• Performs driver-independent preprocessing for IRP_MJ_DEVICE_CONTROL requests and dispatches to the appropriate device-specific routines in the tape miniclass drivers.

• Communicates with other drivers in the system to deliver the CDBs to the tape devices.

• Translates between NT status codes and tape status codes, provides device-independent tape-specific error handing, and calls device-specific error handling routines.

• Allocates driver context areas for miniclass drivers (minitape extension and command extension).

The tape class driver is provided as a kernel-mode DLL.

See the Kernel-Mode Driver Reference for descriptions of the TapeClassXxx routines that can be called by a tape miniclass driver.