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Fibre Channel Adapter/1063 User's Guide and Reference

Changeable FC Characteristics

There are three different device entries associated with the FC software: the FC network driver, the FC adapter driver, and the FC adapter. The FC network driver is responsible for managing the transmission and receiving of network data to and from the raw sockets applications or the TCP/IP protocols. The FC adapter driver is responsible for managing the FC adapter. Following are the changeable attributes for each device entry:

Network Driver Characteristics (fcnet)

Transmit Queue Indicates the number of transmit buffers that can be queued for transmission by the device driver. Valid values range from 10 through 300. The default value is 40.

Adapter Driver Characteristics (fcsdd)

Number of Short Transfer Areas Indicates the number of short transfer areas (STAs) allocated by the device driver. The STAs are 2KB pinned-memory buffers that are premapped for DMA. Any I/O operation that requires mapping less than 2K is copied to an STA (if available), which is faster than mapping the buffer for DMA. Performance can be enhanced by increasing this number if the num_sta_rq_dnd statistic in the fcs_stats structure is greater than zero.
ARP Server Support
                          Enables the Fibre Channel adapter to be configured as an ARP server. A value of no configures the adapter for normal operation. A value of yes configures the adapter as an ARP server.

Adapter Characteristics (fcs)

Width of Transmit Bus
Memory used for DMA
                          Affects the number and the size of outstanding I/O operations possible on this adapter. The number should be increased if the num_tcw_rq_dnd statistic maintained in the fcs_stats structure indicating that the translation is greater than zero. Generally, the more protocol heads and applications running over this device, the higher the number should be. If the number is too low, and the num_tcw_rq_dnd statistic is greater than zero, then performance has been degraded.
Width of Receive Bus
Memory used for DMA
                          Affects the number of receive buffers allocated for unsolicited incoming data from this adapter. If this number is too low, a user will not be able to request the desired number of receive buffers (through the add_filter service), and will therefore not be able to receive unsolicited incoming data. The number should be increased if this behavior is observed.
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