The Ultra160 SCSI host adapters automatically control SCSI bus termination for various bus configurations.
In one case, you may disable termination by using BIOS software control to change the BIOS termination from Automatic to Off.
In another case where jumpers are provided on the board, you would locate the shunts on the board for autotermination override. Termination can be disabled by placing a manual shunt over the post. When the shunt is off, the terminator is active. When the shunt is on the post, the terminator is disabled. Figure 2.7 illustrates how the shunt controls autotermination.
Figure 2.7 Autotermination Shunt
Autotermination enabled (no jumper installed)
Termination disabled (jumper installed)
2.3.1Internal and External SCSI Terminations
If you are making internal SCSI device connections to your host adapter, you must terminate the last internal device on the SCSI bus. If you are making external SCSI device connections to your host adapter, you must terminate the last external device on the SCSI bus. You must disable the termination on all other devices. Termination on your host adapter is automatically enabled in this case.
2.3.2Setting SCSI IDs
You must set each SCSI device and the host adapter to a separate SCSI ID. The IDs are 0 through 7 for an
If you plan to boot your computer from a hard disk drive on the SCSI bus, that drive should have SCSI ID 0, or the lowest SCSI ID on the bus. Normally, you do not change the host adapter SCSI ID setting. If you wish to do so, refer to the PCI Storage Device Management System SDMS 4.0 User’s Guide, which explains how to set your host adapter ID using the SCSI BIOS Configuration Utility.
Terminating the SCSI Bus |