Knowledge Base - Glossary

• rank
  A variable commonly used in MPI functions. Assigns each process a unique integer rank from 0 to (the number of processes - 1), which determines the rank of the calling process within the communicator. The master process has the rank of 0.
• rack
  Within NAS, the term "rack" refers to the physical housing that connects each of the components of the supercomputers. NAS systems are SGI Altix 4000/ICE and SGI UV 2000 architecture types. See IRU.
• RDMA
  Remote Direct Memory Access; direct memory access from the memory of one computer into that of another without involving either one's operating system. This permits high-throughput, low latency networking, which is especially useful in massively parallel computer clusters. The InfiniBand fabrics (ib0 and ib1) that interconnect the NAS systems allows for RDMA communications via a message passing interface (MPI). See KB article 100.