SCSI(4) 						     Kernel Interfaces Manual							   SCSI(4)

Name
       SCSI - Small Computer System Interconnect

Description
       The  ULTRIX  system interfaces to disk and tape devices through the Small Computer System Interconnect (SCSI).  Initial ULTRIX SCSI support
       is limited to the Digital-supplied mass storage devices.  The following devices are fully supported on the ULTRIX system:

       o    Winchester disks: RZ22, RZ23, RZ23L, RZ24, RZ55, RZ56, RZ57, RX23, RX26, RX33

       o    Magnetic tapes: TZ30, TZK50, TLZ04, TSZ05, TKZ08, TZK10

       o    Optical disks: RRD40, RRD42

       Under the ULTRIX operating system, a SCSI device is referred to by its logical name.  Logical names take the following form:
       nn#
       The nn argument is the two-character name; the number sign (#) represents the unit number.  The two character names for SCSI devices are:

       rz  -  RZ22, RZ23, RZ23L, RZ24, RZ55, RZ56, RZ57, RX23, RX26, RX33, RRD40, RRD42 disks

       tz  -  TZ30, TZK50, TLZ04, TSZ05, TKZ08, and TZK10 tapes

       The unit number is a combination of the SCSI bus number, either 0, 1, ... and the device's target ID number.   The  unit  number  is  eight
       times  the  bus	number plus the target ID.  For example, an RZ23 disk at target ID 3 on bus 0 would be referred to as rz3; a TZK50 tape at
       target ID 5 on the second SCSI bus would be referred to as 13.

       The SCSI bus has eight possible target device IDs.  By default, one is allocated to the system.	This allows for a maximum of seven  target
       devices connected to a SCSI bus.

Restrictions
       The ULTRIX SCSI device driver does not operate with optical disks, other than the Digital-supplied devices.

       The SCSI driver attempts to support on a best effort basis, non-Digital-supplied winchester disks and magnetic tapes.

       The following notes apply to the driver's handling of non-Digital-supplied disks:

	  o   These disks are assigned a device type of RZxx, instead of RZ22, RZ23, RZ23L, RZ55, RZ56, RZ57, RX23, RX26, or RX33.  The RZxx disks
	      follow the same logical device naming scheme as the Digital-supplied disks.

	  o   During the autoconfigure phase of the system startup, the driver prints the contents of the SCSI vendor  ID,  product  ID,  and  the
	      revision level fields of the inquiry data return by the SCSI device.

	  o   RZxx  disks  are	assigned a default partition table. The default table can be modified by editing the sz_rzxx_sizes[8] entry in the
	      file The utility can also be used to modify the partition table on a RZxx disk.

	  o   The only logical unit number (LUN) supported for each target ID is 0.

See Also
       rz(4), tz(4), chpt(8)

																	   SCSI(4)