External SCSI Cabling and Termination

Use the following cabling guidelines to ensure proper device cabling and termination on the external SCSI bus:

• In order to maintain UltraSCSI performance, all cables used must be UltraSCSI-compliant.

• The external SCSI bus must be correctly terminated. Most Sun devices use autotermination. See the documentation supplied with the device.

• If all external mass storage devices use 68-pin connectors, connect all non-Sun devices to the system first and connect a Sun autoterminating device to the end of the chain.

• If external mass storage devices consist of 68-pin devices and 50-pin devices, connect the Sun 68-pin devices to the system first and terminate the chain with a 50-pin device and its terminator. The 68-pin device connected to the 68-50 pin adapter cable must be autoterminating in order to terminate the high-order bits.

Do not connect 68-pin devices after 50-pin devices; SCSI bus errors will occur.

The following figures provide a summary of the cabling guidelines.

Figure 5-13