Cray XT

Cray XT
Name	Cray XT
Developer	Cray Inc.
Family	XT series
Release	2006
Discontinued	2011
Cpu	AMD Opteron
Memory	DDR2 SDRAM
Os	UNICOS/lc
Purpose	Supercomputing

Cray XT

Overview

The Cray XT was a line of supercomputers introduced by Cray Inc. in 2006 that targeted high-performance computing centers such as Oak Ridge National Laboratory, Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Sandia National Laboratories, and National Center for Supercomputing Applications with systems designed for computational science workloads, climate modeling, astrophysics simulations, quantum chemistry calculations, and national security applications using commodity AMD processors and custom interconnects derived from earlier designs like those at Cray Research and projects involving organizations from Department of Energy programs and collaborations with vendors such as Sungard and SGI.

Architecture and Hardware

The architecture combined multi-core 64-bit AMD Opteron processors, shared and distributed memory configurations, coherent memory controllers, high-bandwidth DDR2 SDRAM channels, and a three-dimensional torus or mesh interconnect topology influenced by network research from institutions including Sandia National Laboratories, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, and companies like Quadrics and Myrinet manufacturers; system cabinets housed compute blades, service nodes, and routers integrated with cooling systems developed in consultation with firms like Emerson Electric and Liebert to meet thermal design requirements for sites such as Argonne National Laboratory, CERN, and National Oceanic and Atmospheric Administration data centers.

Software and Operating Environment

Cray XT systems ran a lightweight operating environment derived from UNICOS variants named UNICOS/lc and managed batch scheduling with middleware and resource managers like PBS Professional, Torque (software), and integration points for Slurm Workload Manager at centers including NERSC, PSC, and TeraGrid partners; programming environments supported compilers and tools from GNU Compiler Collection, PGI Compilers, and vendor toolchains alongside parallel libraries such as MPI, OpenMP, BLAS, and science packages used by researchers at Princeton University, MIT, Stanford University, and Caltech.

Performance and Benchmarks

Performance on LINPACK and domain-specific benchmarks demonstrated scaling behavior reported at conferences like the TOP500 lists, SC Conference, and ISC High Performance where XT installations delivered multi-teraflop to petaflop-class performance using system-level optimizations, benchmarked by teams from Oak Ridge National Laboratory, National Center for Atmospheric Research, NASA Ames Research Center, and academic groups from University of Illinois Urbana–Champaign and University of Texas at Austin using codes such as NAMD, GROMACS, LAMMPS, and climate models like Community Earth System Model.

Models and Variants

The family included multiple models and upgrades produced between 2006 and 2011 with chassis and cabinet variants used in deployments at Fujitsu-partnered sites and government labs; notable iterations incorporated improved AMD core counts, memory density increases, and revised interconnect hardware with router blades and network adaptations influenced by research from Cray Research, Sequent Computer Systems, and collaborative projects involving Intel and IBM researchers who influenced later design directions while organizations such as Department of Defense contractors and national laboratories evaluated configurations for classified and unclassified workloads.

Deployment and Use Cases

XT systems were deployed for scientific simulations in astrophysics at Harvard–Smithsonian Center for Astrophysics and Max Planck Society facilities, materials science at Argonne National Laboratory and Oak Ridge National Laboratory, computational biology at Broad Institute and Scripps Research, weather prediction at National Weather Service and European Centre for Medium-Range Weather Forecasts, and energy research collaborations with ExxonMobil and Shell for reservoir modeling, with procurement and deployment supported by procurement offices at agencies like National Science Foundation and Department of Energy.

Legacy and Successors

The XT line influenced successor architectures and commercial strategies at Cray and partner companies, informing designs used in later Cray systems and acquisitions involving Hewlett Packard Enterprise, Siemens, and integration into national initiatives such as CORAL and successor procurements at Oak Ridge National Laboratory and Lawrence Livermore National Laboratory; the technological lineage can be traced to subsequent systems that embraced many-core processors, advanced interconnects, and heterogeneous accelerators evaluated by researchers at NVIDIA, AMD, Intel, and institutions participating in exascale roadmaps like DOE Exascale Computing Project.

Category:Supercomputers