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Appendix B. CA Option Settings
110 Error Alert
Warning: The CA parameters do not take effect until the 3745 has gone through
a power OFF/ON procedure, or a general IPL from the control panel.
(Function
=
0) has been done.
I/O error alert is a channel interface feature that detects a CA malfunction
(disconnect-in tag line raised). This information (Y or N) can be selected when
the I/O error alert feature is present in the attached host.
• I/O error alert is supported by all the IBM hosts to which
a
3745
can be
attached (308X, 3090*,
4341, 4361, 4381,
ES/9000* and 937X). In case of
a
non-IBM attached host, ensure that the I/O error alert feature is present in
that host.
• When the TPS feature is present and if both interfaces are connected to two
different hosts, I/O error alert can be set to YES only if the two hosts support
the I/O alert feature.
Two-Processor Switch Mode (TPS/TCS)
When the TPS feature is pres-ent, you can select either TPS or TCS mode.
• In TPS mode, the A and B interfaces are connected to the same host and
can be enabled at the same time.
• In TCS mode, the interfaces A and B are connected to channels of two dif-
ferent hosts/processors or to two channels of a unique host/processor and
cannot work at the same time.
Channel Burst Length
This information
(4
to
254)
is mandatory. An even value must be entered.
When using the TPS feature, the burst length must be specified for both the A
and B interfaces of the channel adapter.
Recommended values to allow a better CA throughput are given hereafter.
When working through a block multiplexer channel, selector channel, or byte
multiplexer channel with buffered devices on the channel, the burst length
recommended value is 64 (NCP* and PEP) for CADS and 254 for a BCCA.
When working through a byte multiplexer channel without buffered devices on
the channel, the burst length recommended value is: 32 for 308X or 3090 or
ES/9000, 16 for 4341 or 4381, 8 for 4361.
Notes:
©
COPYright IBM Corp. 1989, 1991
• The CA throughput depends also on the 10C bus load, and the burst
length must be discussed with the customer in any case.
• Value
254
may be used for
a
byte multiplexer channel if the user wants
to optimize the efficiency (connect time) instead of the throughput.
B-1
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