Chapter 1. IBM Flex System FC3171 8 Gb SAN Switch - QLogic

I/O Stream Guard
The I/O Stream Guard feature suppresses the Registered State Change Notification
(RSCN) messages on a port basis. I/O Stream Guard should be enabled only on
ports connected to initiator devices. To configure the I/O Stream Guard option
using the Port Properties dialog, open the Port menu, and select Port Properties.
Select the option that corresponds to one of the following options:
• Enable—suppresses the reception of RSCN messages from other ports for which
I/O Stream Guard is enabled.
• Disable—allows free transmission and reception of RSCN messages.
• Auto—suppresses the reception of RSCN messages when the port is connected
to an initiator device with a QLogic HBA. For older QLogic adapters, such as the
QLA2200, Device Scan must be enabled. The default is Auto. See ”Device scan”
on page 5-94.
Device scan
The Device Scan feature queries the connected device during login for FC-4
descriptor information. Disable this parameter only if the scan creates a conflict
with the connected device.
Auto performance tuning and AL fairness
The Auto Perf Tuning and AL Fairness settings are configured using the Advanced
Port Properties dialog shown in Figure 39. The Auto Perf Tuning option enables the
switch to dynamically control the MFS_Enable, VI_Enable and LCF_Enable features
based on the operational state of the port.
The AL Fairness option controls how frequently the switch can arbitrate for access.
Once a port has arbitrated and won access to the loop, it does not try again until all
others have had an opportunity to arbitrate for the loop. This setting applies only to
ports running in loop (FL) mode.
To open the Advanced Port Properties dialog, select one or more ports, open the
Port menu, and select Advanced Port Properties.
Figure 39. Advanced Port Properties dialog
94 IBM Flex System FC3171 8 Gb SAN Switch QuickTools User’s Guide