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Titan System Overview

See this article in context within the following user guides: Titan

With a theoretical peak performance of more than 20 petaflops, Titan, a Cray XK7 supercomputer located at the Oak Ridge Leadership Computing Facility (OLCF), gives computational scientists unprecedented resolution for studying a whole range of natural phenomena, from climate change to energy assurance, to nanotechnology and nuclear energy.

Compute Partition

Titan contains 18,688 physical compute nodes, each with a processor, physical memory, and a connection to the Cray custom high-speed interconnect. Each compute node contains (1) 16-core 2.2GHz AMD Opteron™ 6274 (Interlagos) processor and (32) GB of RAM. Two nodes share (1) Gemini™ high-speed interconnect router. The resulting partition contains 299,008 traditional processor cores, and (598) TB of memory.

Specialized NVIDIA Accelerators
The OLCF provides a comprehensive Accelerated Computing Guide that covers the use of Titan’s NVIDIA Kepler™ accelerators.

In addition to the Opteron CPU, all of Titan’s 18,688 physical compute nodes contain an NVIDIA Kepler™ accelerator (GPU) with 6 GB of DDR5 memory.

External Login Nodes

Upon login, users are placed onto login nodes by default. Each Titan login node houses an 8-core AMD Opteron™ 6140-series CPU and (256) GB of RAM.

Network Topology

Nodes within the compute partition are connected in a three-dimensional torus. This provides a very scalable network with low latency and high bandwidth.

File Systems

The OLCF’s center-wide Lustre® file system, named Spider, is available on Titan for computational work. Spider contains over 26,000 clients and (32) PB of disk space. A separate, NFS-based file system provides $HOME storage areas, and an HPSS-based file system provides Titan users with archival spaces.

Operating System

Titan employs the Cray Linux Environment as its OS. This consists of a full-featured version of Linux on the login nodes, and a Compute Node Linux microkernel on compute nodes. The microkernel is designed to minimize partition overhead allowing scalable, low-latency global communications.