Titan (supercomputer)

Titan

Active	Became operational October 29, 2012; decommissioned August 2, 2019
Sponsors	US DOE and NOAA (<10%)
Operators	Cray Inc.
Location	Oak Ridge National Laboratory
Architecture	18,688 AMD Opteron 6274 16-core CPUs 18,688 Nvidia Tesla K20X GPUs
Power	8.2 MW
Operating system	Cray Linux Environment
Space	404 m2 (4352 ft2)
Memory	693.5 TiB (584 TiB CPU and 109.5 TiB GPU)
Storage	40 PB, 1.4 TB/s IO Lustre filesystem
Speed	17.59 petaFLOPS (LINPACK) 27 petaFLOPS theoretical peak
Cost	US$97 million (equivalent to $129 million in 2023)
Ranking	TOP500: 4th, June 2017[1]
Purpose	Scientific research
Legacy	Ranked 1 on TOP500 when built. First GPU based supercomputer to perform over 10 petaFLOPS
Website	www.olcf.ornl.gov/titan/

Titan or OLCF-3 was a supercomputer built by Cray at Oak Ridge National Laboratory for use in a variety of science projects. Titan was an upgrade of Jaguar, a previous supercomputer at Oak Ridge, that uses graphics processing units (GPUs) in addition to conventional central processing units (CPUs). Titan was the first such hybrid to perform over 10 petaFLOPS. The upgrade began in October 2011, commenced stability testing in October 2012 and it became available to researchers in early 2013. The initial cost of the upgrade was US$60 million, funded primarily by the United States Department of Energy.

Titan was eclipsed at Oak Ridge by Summit in 2019, which was built by IBM and features fewer nodes with much greater GPU capability per node as well as local per-node non-volatile caching of file data from the system's parallel file system.^[2]

Titan employed AMD Opteron CPUs in conjunction with Nvidia Tesla GPUs to improve energy efficiency while providing an order of magnitude increase in computational power over Jaguar. It used 18,688 CPUs paired with an equal number of GPUs to perform at a theoretical peak of 27 petaFLOPS; in the LINPACK benchmark used to rank supercomputers' speed, it performed at 17.59 petaFLOPS. This was enough to take first place in the November 2012 list by the TOP500 organization, but Tianhe-2 overtook it on the June 2013 list.

Titan was available for any scientific purpose; access depends on the importance of the project and its potential to exploit the hybrid architecture. Any selected programs must also be executable on other supercomputers to avoid sole dependence on Titan. Six vanguard programs were the first selected. They dealt mostly with molecular scale physics or climate models, while 25 others were queued behind them. The inclusion of GPUs compelled authors to alter their programs. The modifications typically increased the degree of parallelism, given that GPUs offer many more simultaneous threads than CPUs. The changes often yield greater performance even on CPU-only machines.