Administrative Traffic

As mentioned earlier, a Sun HPC cluster generates the same kind of network traffic as any UNIX-based LAN. Common operations like starting a program can have a significant network impact. The impact of such administrative traffic should be considered when making network configuration decisions.

When a simple serial program is run within a LAN, network traffic typically occurs as the executable is read from a NFS-mounted disk and paged into a single node's memory. In contrast, when a 16- or 32-process parallel program is invoked, the NFS server is likely to experience approximately simultaneous demands from multiple nodes--each pulling pages of the executable to its own memory. Such requests can often result in large amounts of network traffic. How much traffic occurs will depend on various factors, such as the number of processes in the parallel job, the size of the executable, and so forth.