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Communication benchmarks with the Ancor Fibre Channel Fabric


The aim of this work is to measure communication times for transferring data from memory to memory between RS/6000 IBM workstations via a 16 port Ancor Fibre Channel Fabric (or Switch). In fact, not only the performance of the switch is measured, but also the performance of the interfaces and the software (drivers).

Figure 1 shows the experimental hardware configuration used. One machine is a 250 model with a PowerPC 601 processor at 66 MHz, the second one is a 590 model with a Power2 processor at 66 MHz, and the third one is a C10 model with a PowerPC 601 at 80 MHz. A MCA CIM (Micro Channel Architecture Communications Interface Module) 250 Ancor adapter is located in each workstation to provide access to the Fibre Channel world

Figure 1: Experimental hardware configuration.

The MCA CIM 250 interface to the MCA bus (RS/6000 IBM workstation) is a 32 bit bus Master capable of data transfer rates up to 40 MBytes/s and it should not represent a bottleneck in this system, where the speed of each 50 micron optic fibre is 266 Mbits/s. For more details about the Fibre Channel Standard, the Fibre Channel fabric and adapters, see [1], [2], [3] and [4].

The driver available for MCA CIM 250 adapters can support two different interfaces:

Much of the overhead of TCP/IP's reliability checks is redundant, because the FCS/MCA system protects the integrity of data transfers. The Direct Channel interface feature of the driver allows the replacement of the TCP and IP levels of protocol with a direct connection to the driver, thereby achieving the highest possible bandwidth.

We performed transmission tests using both interfaces albeit for our application we are interested in using the most optimized one (providing the best bandwidth), viz the Direct Channel interface. Results are reported hereinafter.

Fabrice Chantemargue - 30 AUG 94
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