FIBRE CHANNEL PERFORMANCES WITH IBM EQUIPMENT
The aim of this work was to measure communication performances at the user level when exchanging data between IBM workstations via an eight port IBM Fibre Channel Fabric (or switch). Similar tests have already been performed at CERN with different kinds of equipment on heterogeneous systems (IBM and HP workstations with different power, ANCOR and IBM Fibre Channel interfaces, ANCOR Fibre Channel Fabric) with different kernel configuration , ,  and .
Thanks to IBM-ECSEC at Rome, the test with the following homogeneous hardware configuration has been made feasible:
The six workstations were RS/6000-560 machines with a POWER architecture running at 50 Mhz. The IBM Fibre Channel interfaces to the MCA bus (RS/6000 IBM workstation) are 32 bit bus Master capable of data transfer rates up to 40 MBytes/s: they do not represent a bottleneck in the system, where the speed of each 50 micron optic fibre is 266 Mbits/s. The Fibre Channel equipment is implementing version 4.3.
The commercial driver available from IBM  for the Fibre Channel adapters offers two different API (Application Programming Interface):
We performed transmission tests using both APIs and results are reported hereinafter.
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