Cray XT3
The Cray XT3 is a distributed memory massively parallel MIMD supercomputer designed by Cray Inc. with Sandia National Laboratories under the codename Red Storm. Cray turned the design into a commercial product in 2004. The XT3 derives much of its architecture from the previous Cray T3E system, and also from the Intel ASCI Red supercomputer.
The XT3 is comprised of between 192 and 32,768 processing elements (PEs), where each PE comprises a 2.4 GHz AMD Opteron processor, a custom SeaStar communications chip, and between 1 and 8 GB of RAM. The PowerPC 440 based SeaStar device provides a 6.4 gigabyte per second connection to the processor across HyperTransport, as well as six 8-gigabyte per second links to neighboring PEs. The PEs are arranged in a 3-dimensional torus topology, with 96 PEs in each cabinet.
The XT3 runs an operating system called UNICOS/lc. This comprises two components; the Compute PEs run a microkernel called Catamount, which derives from the SUNMOS OS of the Intel Paragon; Service PEs (consisting of System, Input/Output (I/O), Network and Login PEs) run the Linux kernel. I/O PEs use physically distinct hardware, in that the node boards include PCI-X slots for connections to Ethernet and Fibre Channel networks.
Though the performance of each XT3 model will vary with the speed and number of processors installed, the Cray datasheets describes a 24 cabinet model as providing 23.4 teraflops of peak performance.