IBM SG24-4576-00 User Manual
Page 93
The fields on this panel are described as follows:
SCSI Parity Checking:
Select this option to enable or disable SCSI Parity
checking on the host adapter. If enabled, the host adapter will check parity when
reading from the SCSI bus to verify the correct transmission of data from your
SCSI devices. SCSI Parity checking should be disabled if any attached SCSI
device does not support SCSI parity. Most currently available SCSI devices do
support SCSI parity.
Host Adapter SCSI termination:
All SCSI interfaces use daisy-chain cabling.
The cable starts at the adapter and goes to the first device, and then out of that
device to the next device and so on until it reaches the last device in the chain.
The last device has an incoming cable and a
terminator. The terminators are
used to absorb potential signal reflections on the SCSI bus which would cause
interference. The last device on the bus must always be terminated.
The SCSI-2 Fast/Wide PCI adapter that came with the PCI/EISA server has three
connectors which can be the starting points for a daisy-chained cable: one 8-bit,
50-pin (SCSI-I) internal connector, one 16-bit, 68-pin (SCSI-II Wide) internal cable
connector, plus another 16-bit, 68-pin external connector. The adapter has
built-in terminators on these connectors.
The setting for the Host Adapter SCSI termination needs to be configured
depending on which connectors are used. This option is comprised of two
entries, a low and a high. You can think of them as software jumpers. Each
entry, low and high, can take on either an on or off value, thereby giving four
possible different combinations of the two entries. The chart below shows the
proper values of these entries depending upon what connectors have been used.
Note
Only two of the three connectors can be used, either the two internal or one
internal and one external.
After configuring the host adapter, you need to configure the SCSI devices. To
do this:
•
Use the arrow keys to select SCSI Device Configuration
•
Press Enter
A screen like the one in Figure 36 on page 80 will appear:
Table 16. Host Adapter SCSI Termination Parameter
16-bit (68pin)
internal connector
8-bit (50pin)
internal connector
16-bit (68pin)
external
connector
Low
value
High
value
Yes
On
On
Yes
On
On
Yes
On
On
Yes
Yes
Off
Off
Yes
Yes
Off
On
Yes
Yes
Off
On
Chapter 3. H a r d w a r e Configuration
79