Adaptec 131U2 - AAA RAID Controller, Инструкция по установке и эксплуатации оборудования, Страница: 21 / 82

2-7
Installing the Hardware
Terminate the Ends
To ensure reliable communication on the SCSI bus, terminators must
be installed (or enabled) on the devices at the physical ends of each
SCSI channel. The devices between the physical ends of each SCSI
channel must have the terminator removed (or disabled).
Terminating SCSI Channels on the AAA-131U2/133U2 RAID Card
Termination on the AAA-131U2/133U2 itself is controlled via the
SCSISelect
™
utility. We recommend that you leave each channel on
the AAA-131U2/133U2 set to its default setting of Auto Mode (the
terminators are enabled or disabled according to the SCSI
connectors in use). If you want to manually disable the
AAA-131U2/133U2 termination setting, see Chapter A, Using
SCSISelect and Disk Utilities.
Terminating SCSI Devices
On most internal SCSI devices the termination setting is controlled
by setting a jumper or a switch, or by physically removing or
installing a resistor module(s). On most external SCSI devices,
termination is controlled by installing or removing a terminating
plug (see Figures 2-14 and 2-15 on page 2-17). Read the device’s doc-
umentation to determine how to enable or disable termination on
your particular device.
The internal SCSI cables supplied in an Adaptec AAA-131U2/133U2
kit have a terminator attached. If you have this type of cable, disable
termination on all internal SCSI devices connected to the cable. In
general, we recommend that you terminate the internal cable
instead of terminating the SCSI devices. If you are using an external
array enclosure, we recommend that you terminate the SCSI back-
plane or install an active terminator on the second SCSI connector
on the rear panel instead of terminating the individual SCSI devices.
If you follow these recommendations, SCSI bus termination will not
be affected when you remove or replace SCSI devices.
Note:
We recommend that you enable termination power on
all SCSI devices in the system so that termination power
will still be supplied if you replace one or more drives on
the SCSI bus.