11-11-2007 02:21 PM
With today's high speed hard drives combined with long cable runs, only use high quality 'twisted pair' cable and external active (cable end) terminators. Active termination boosts data integrity and reliability. With active termination, a 110-ohm resistor on each signal line connects to a voltage regulator. The regulator ensures signal quality over the entire length of the SCSI bus. This reduces under and overshoot signals typically found on passive resistor termination schemes
Passive termination draws its electrical power from the SCSI host adapter. A 220/330-ohm resistor is used to provide the necessary impedance to prevent the data signal from 'reflecting' back. Fluctuations in termination power (or failing cables) can show up as error symptoms in the drive, yet do not originate there. In general we recommend you enable SCSI Termination Power if available.