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:
•Winchester disks: RZ22, RZ23, RZ24, RZ55, RZ56, RZ57, RX23
•Magnetic tapes: TZ30, TZK50, TLZ04, TSZ05
•Optical disks: RRD40
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, RZ24, RZ55, RZ56, RZ57, and RRD40 disks
tz- TZ30, TZK50, TLZ204, and TSZ05 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:
•These disks are assigned a device type of RZxx, instead of RZ22, RZ23, RZ55, RZ56, or RZ57. The RZxx disks follow the same logical device naming scheme as the Digital-supplied disks.
•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.
•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 /usr/sys/data/scsi_data.c. The chpt utility can also be used to modify the partition table on a RZxx disk.
•The only logical unit number (LUN) supported for each target ID is 0.