SCSI Termination

The SCSI bus on a SCSI channel is an electrical transmission line. It must be terminated properly to minimize reflections and losses. You complete the SCSI bus by setting termination at both ends. MegaRAID automatically provides SCSI termination at one end of the SCSI bus for each channel. Terminate the other end of the bus by attaching an external SCSI terminator module to the end of the cable for each channel or by attaching a SCSI device that internally terminates the SCSI bus at the end of each SCSI channel.

MegaRAID should always terminate each of the four SCSI buses if devices are attached to either the internal or external SCSI connectors, but not to both.

Use standard external SCSI terminators on SCSI channels operating at 10 MB/s or higher synchronous data transfer.

Terminating Internal SCSI Disk Arrays Set the termination so that SCSI termination and termination power are intact when any disk drive is removed from a SCSI channel, as shown below. MegaRAID termination should always be enabled or controlled by software. Make sure J2, J3, J5, and J7 are either always open (termination always enabled), or Pins 1-2 are shorted (termination controlled by software).

Cont’d

Chapter 6 Hardware Installation

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