Connecting External Options
termination setting of the SCSI-2 adapter in the SCSISelect utility
program, as described in “Using the SCSISelect Utility Program”
on page 303, so that the SCSI-2 adapter is no longer terminated.
If you attach only external devices to the SCSI-2 adapter, you
must terminate the last device on the cable. If you install only
one external device, it must be terminated. Since the SCSI-2
adapter is already terminated, do not change the termination
setting.
Cabling Requirements
If you plan to install external SCSI devices, you must order an
additional SCSI cable. That is, to use external devices with the PC
Server 520, you must connect them to the SCSI-2 adapter, using a
SCSI cable. Before you install external SCSI devices, you must have
the correct external SCSI cables. See Table 2 on page 273 for
information on cable lengths. The cables must have the proper
connector for the SCSI-2 adapter on one end, and the proper
connector for the first external device on the other end. To select
and order the correct cables for use with external devices, contact
your IBM reseller or IBM marketing representative.
The SCSI-2 Fast/Wide PCI Adapter can support a total of 15 devices
and the PC ServeRAID Adapter can support a total of 45 devices.
However, you must not exceed the maximum cable lengths listed in
Table 2 on page 273.
If you are using a SCSI data transfer rate greater than 5 MB per
second, the maximum length of the SCSI bus (cable) must not
exceed 3 meters (9.8 feet). If you are using a SCSI data transfer rate
of 5 MB per second or slower, the maximum length of the SCSI bus
cable must not exceed 6 meters (19.7 feet). These lengths apply to
the combined lengths of the internal and external cables. Adhering
to these standards ensures that your server operates properly.
272 PC Server 520 User's Handbook for PCI/EISA
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