Brocade FICON Administrator’s Guide (Supporting Fabric OS v7.3.0) - Manual (Page 65)

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Considerations for setting mode register bits
Consider the following when changing mode register bits:
• The UAM bit can only be set by host programming.
• All mode register bits except UAM are saved across power cycles; the UAM bit is reset to 0
following a power-on.
• Mode register bits can be changed when the switch is offline or online. If the ACP or HCP bits are
changed when the switch is online, they will take effect any time between the completion of the
current command and the end of the CCW command chain (or the next alternate manager
operation).
Setting the mode register bits
Perform the following steps to set mode register bits:
1. Connect to the switch and log in using an account assigned to the admin role.
2. Enter the ficonCupSet modereg command to set the FICON CUP mode register bits for the local
switch.
Example of setting the mode register bit HCP to off
switch:admin> ficoncupset modereg HCP 0
Example of setting the mode register bit ACP to on
switch:admin> ficoncupset modereg ACP 1
Setting the MIHPTO value
The missing interrupt handler primary timeout (MIHPTO) value determines how long the channel will
wait before timing out an expected response from the CUP. This value is part of the data returned to the
host when it reads the configuration data, but the host is under no obligation to adhere to this value. The
actual value that the host will use before detecting a timeout can be set by the system programmer
(overriding the value returned by the switch).
Use the ficonCupSet MIHPTO command to increase, decrease, or display the MIHPTO value that the
CUP returns to the host when configuration data is read. Changing the MIHPTO value requires that the
CUP control device be varied offline from the host, as the host will not automatically be notified when
the value is changed. The host will normally read the new value using the Read Configuration Data
command when the CUP is varied back online.
The MIHPTO setting will persist across reboots, power on reset (POR), and failovers. Setting this value
to the upper end of the time range will allow the CUP more time to process requests during intervals of
peak usage, without causing the host to detect timeouts. It is recommended that the value be set to 180
seconds (default).
Complete the following steps to set the MIHPTO value.
1. Connect to the switch and log in using an account assigned to the admin role.
2. Enter the ficonCupSet MIHPTO command and set the value from 15 through 600.
Considerations for setting mode register bits
FICON Administrator's Guide 63
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