Apple Workgroup Server 6150/66 - Manual (Page 54)

5 Make sure that only the last device in the SCSI chain has a terminator.
To ensure accurate transmission of information, a terminator must be at each
end of a SCSI chain. Your internal hard disk, which is the first device in the
chain, has a built-in terminator.
Some external SCSI devices from manufacturers other than Apple have a built-
in terminator. (Check the information that came with the device.) If the device
at the end of the SCSI chain does not have a built-in terminator, you need to
attach an external terminator.
Have your Apple-authorized service provider remove any extra built-in
terminators. You can attach or remove external terminators yourself.
Note: If only one external device has a built-in terminator, rearrange the SCSI
chain so that device is at the end.
IMPORTANT Always turn on any external SCSI devices connected to your
server before turning on the server itself. Otherwise, your server cannot
recognize the SCSI devices.
Installing a device driver
A device driver is software that lets the server communicate with a particular
SCSI device.
Note: If you have set up your server and connected additional devices, but not
yet turned the server on, return to the section “Plugging In the Server” in
Chapter 1 before installing a device driver.
External SCSI terminator
38 Chapter 3 / Expanding Your Server and Connecting Other Equipment