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{{short description|American supercomputer}}
{{About|the Titan supercomputer|the Atlas 2 prototype computer|Titan (1963 computer)}}
{{good article}}
{{Use mdy dates|date=March 2013}}
{{Infobox custom computer {{Infobox custom computer
| Image = ] | Image = Titan, 2013 (49912802521).jpg
| Caption = | Caption = Titan in 2013
| Dates = Became operational October 29, 2012 | Dates = Became operational October 29, 2012; decommissioned August 2, 2019
| Operators = ] | Operators = ]
| Sponsors = ] and ] (<10%) | Sponsors = ] and ] (<10%)
| Location = ] | Location = ]
| Architecture = 18,688 ] 6274 16-core CPUs<br>18,688 ] K20X GPUs<br>] | Architecture = 18,688 ] 6274 16-core CPUs<br>18,688 ] K20X GPUs
| Memory = 710&nbsp;] (598&nbsp;TB CPU and 112&nbsp;TB GPU) | Memory = 693.5&nbsp;] <small>(584&nbsp;TiB CPU and 109.5&nbsp;TiB GPU)</small>
| Storage = 10&nbsp;], 240&nbsp;GB/s IO | Storage = 40&nbsp;], 1.4&nbsp;TB/s IO ]
| Speed = 17.59 ] (])<br>27 petaFLOPS theoretical peak | Speed = 17.59 ] (])<br>27 petaFLOPS theoretical peak
| Power = 8.2 ] | Power = 8.2 ]
| Space = 404 sqm (4352 sq ft) | OS = ]
| Cost = US$97 million | Space = 404&nbsp;m<sup>2</sup> (4352&nbsp;ft<sup>2</sup>)
| Cost = US$97 million (equivalent to ${{Inflation|US|97|2012}}&nbsp;million in {{Inflation/year|US}})
| ChartName = ] | ChartName = ]
| ChartPosition = #1 | ChartPosition = 4th
| ChartDate = June 2017<ref>, ], 19 June 2017 (page visited on 19 June 2017).</ref>
| ChartDate = November 12, 2012<ref name=top500>{{cite web|title=Oak Ridge Claims No. 1 Position on Latest TOP500 List with Titan|url=http://www.top500.org/blog/lists/2012/11/press-release/|publisher=]|accessdate=November 15, 2012|date=November 12, 2012}}</ref>
| Purpose = Scientific research | Purpose = Scientific research
| Legacy = Ranked 1 on ] when built.<br>First GPU based supercomputer to perform over 10 petaFLOPS | Legacy = Ranked 1 on ] when built.<br>First GPU based supercomputer to perform over 10 petaFLOPS
| Emulators = | Emulators =
| Website = {{URL|http://www.olcf.ornl.gov/titan/}} | Website = {{URL|http://www.olcf.ornl.gov/titan/}}
}} }}
'''Titan''' or '''OLCF-3''' was a ] built by ] at ] for use in a variety of science projects. Titan was an upgrade of ], a previous supercomputer at Oak Ridge, that uses ]s (GPUs) in addition to conventional ]s (CPUs). Titan was the first such hybrid to perform over 10&nbsp;]. 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 ]60 million, funded primarily by the ].


Titan was eclipsed at Oak Ridge by ] in 2019, which was built by ] and features fewer nodes with much greater GPU capability per node as well as local per-node ] ] of file data from the system's ].<ref>{{cite web |url=https://www.olcf.ornl.gov/summit/summit-faqs/#f9 |title=Summit FAQs |author=<!--Staff writer(s); no by-line.--> |date=2014-11-14 |website=ornl.gov |publisher=Oak Ridge National Laboratory |access-date=2014-11-15}}</ref>
'''Titan''' is a ] developed by ] Inc. at ] for use in a variety of science projects. Titan is an upgrade of ], a previous supercomputer at Oak Ridge, to use ]s in addition to conventional ]s and is the first such hybrid to perform over 10&nbsp;]. The upgrade began in October 2011, commenced stability testing in October 2012 and it will be available to researchers in early 2013. The initial cost of the upgrade was ]$60&nbsp;million, funded primarily by the ].


Titan uses ] CPUs in conjunction with ] GPUs to maintain energy efficiency while providing an exponential increase in computational power over Jaguar. It contains 18,688 CPUs paired with an equal number of GPUs with a theoretical peak performance of 27&nbsp;] however in the ] benchmark used for ranking supercomputers by speed it performed at 17.59&nbsp;petaFLOPS. This was enough to take first place in the November 2012 ranking by the ] organisation. Titan employed ] CPUs in conjunction with ] GPUs to improve ] while providing an order of magnitude increase in computational power over Jaguar. It used 18,688&nbsp;CPUs paired with an equal number of GPUs to perform at a theoretical peak of 27&nbsp;petaFLOPS; in the ] used to rank supercomputers' speed, it performed at 17.59&nbsp;petaFLOPS. This was enough to take first place in the November 2012 list by the ] organization, but ] overtook it on the June 2013 list.


Titan is available for any purpose however selection for time on the computer depends on the importance of the project, potential to fully utilise the hybrid architecture and they must run on other supercomputers to avoid dependence solely on Titan. Six "vanguard" codes were selected to be the first to run on Titan dealing mostly with ] or climate models but other projects are also queued for use of the machine. Due to the inclusion of GPUs programmers have had to alter their existing code to properly address the new architecture. The modifications often require a greater degree of parallelism as the GPUs can handle many more ] simultaneously than CPUs however the changes often yield greater performance even on non-GPU based machines. 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 ]s must also be executable on other supercomputers to avoid sole dependence on Titan. Six vanguard programs were the first selected. They dealt mostly with ] or ]s, while 25 others were queued behind them. The inclusion of GPUs compelled authors to alter their programs. The modifications typically increased the degree of ], given that ]s offer many more simultaneous ] than ]s. The changes often yield greater performance even on CPU-only machines.


==History== ==History==
Plans to create a supercomputer capable of 20 petaFLOPS at the ] (OLCF) at Oak Ridge National Laboratory (ORNL) originated as far back as 2005, when Jaguar was built.<ref name=jackwells/> Titan will itself be replaced by an approximately 200&nbsp;petaFLOPS system in 2016 as part of ORNL's plan to operate an ] (1000&nbsp;petaFLOPS to 1&nbsp;exaFLOPS) machine by 2020.<ref name=jackwells/><ref name=wheredowego/><ref name=cnnguns/> The initial plan to build a new 15,000&nbsp;square&nbsp;meter (160,000&nbsp;ft<sup>2</sup>) building for Titan, was discarded in favor of using Jaguar's existing infrastructure.<ref name=titanic/> The precise system architecture was not finalized until 2010, although a deal with Nvidia to supply the GPUs was signed in 2009.<ref name=gaga/> Titan was first announced at the private ] (SC10) on November 16, 2010, and was publicly announced on October 11, 2011, as the first phase of the Titan upgrade began.<ref name=wheredowego/><ref name=contract/>
In order to remain power efficient and up to date with processing power Jaguar had received various upgrades since its creation in 2005 using the XT3 platform and performing at 25 teraFLOPS.<ref name=jag>{{cite web|title=Jaguar: Oak ridge National Laboratory|url=http://www.top500.org/featured/systems/jaguar-oak-ridge-national-laboratory/|publisher=]|accessdate=December 18, 2012}}</ref> By 2008 Jaguar was upgraded to the XT4 platform and performed at 263 teraFLOPS and by 2009 it was expanded using the XT5 platform to perform at 1.4 petaFLOPS.<ref name=jag/> Further upgrades brought Jaguar to 1.76 petaFLOPS before the Titan upgrades began.<ref>{{cite web|title=TOP500 List November 2011|url=http://www.top500.org/lists/2011/11/|publisher=]|accessdate=December 18, 2012}}</ref> Plans to create a supercomputer capable of 20 petaFLOPS at ORNL were in place as far back as 2005, when Jaguar was built, however the hybrid CPU/GPU architecture was not finalised until 2010 and the name "Titan" not until 2011.<ref>{{cite web|title=Discussing the ORNL Titan Supercomputer with ORNL’s Jack Wells.|url=http://theexascalereport.com/content/2012/discussing-ornl-titan-supercomputer-ornl%E2%80%99s-jack-wells|publisher=The Exascale Report|accessdate=December 19, 2012|month=November|year=2012}}</ref> Titan was announced at the private ] (SC10) on November 16, 2010 although a deal with Nvidia to supply the GPUs was signed in 2009.<ref>{{cite web|last=Bland|first=Buddy|title=Where do we go from here?|url=http://computing.ornl.gov/SC10/documents/SC10_Booth_Talk_Bland.pdf|accessdate=December 18, 2012|date=November 16, 2010}}</ref><ref>{{cite web|last=Morgan|first=Timothy Prickett|title=Oak Ridge goes gaga for Nvidia GPUs|url=http://www.theregister.co.uk/2009/10/01/oak_ridge_fermi/|accessdate=December 19, 2012|date=October 1, 2009}}</ref> It was publicly announced on October 11, 2011 as the first phase of the upgrade began.<ref>{{cite web|last=Levy|first=Dawn|title=ORNL awards contract to Cray for Titan supercomputer|url=http://www.ornl.gov/info/press_releases/get_press_release.cfm?ReleaseNumber=mr20111011-00|publisher=]|accessdate=December 19, 2012|date=October 11, 2011}}</ref> Initially a new 15&nbsp;000&nbsp;m<sup>2</sup> (160&nbsp;000&nbsp;ft<sup>2</sup>) building was planned to house the replacement for Jaguar but it was eventually decided to use Jaguar's existing infrastructure.<ref>{{cite web|last=Munger|first=Frank|url=http://www.knoxnews.com/news/2011/mar/07/oak-ridge-lab-to-add-titanic-supercomputer/|title=Oak Ridge lab to add titanic supercomputer|publisher=Knox News|accessdate=December 19, 2012|date=March 7, 2011}}</ref>


Jaguar had received various upgrades since its creation. It began with the ] platform that yielded 25 teraFLOPS.<ref name=jag/> By 2008, Jaguar had been expanded with more cabinets and upgraded to the ] platform, reaching 263 teraFLOPS.<ref name=jag/> In 2009, it was upgraded to the ] platform, hitting 1.4 petaFLOPS.<ref name=jag/> Its final upgrades brought Jaguar to 1.76 petaFLOPS.<ref name=jag500/>
Titan was funded primarily by the US Department of Energy through Oak Ridge National Laboratory. ORNL funding was sufficient to purchase the CPUs but not all of the 18,&nbsp;688 GPUs so the ] agreed to fill the remaining nodes in return for computing time.<ref name=noaa>{{cite web|last=Munger|first=Frank|title=The ORNL and NOAA relationship|url=http://blogs.knoxnews.com/munger/2012/11/the-ornl-and-noaa-relationship.html|publisher=Knox News|accessdate=December 20, 2012|date=November 26, 2012}}</ref><ref>{{cite web|last=Munger|first=Frank|title=The cost of Titan|url=http://blogs.knoxnews.com/munger/2012/11/the-cost-of-titan.html|publisher=Knox News|accessdate=December 20, 2012|date=November 18, 2012}}</ref> ORNL scientific computing chief Jeff Nichols noted that Titan cost approximately $60&nbsp;million upfront of which the NOAA contribution was less than $10&nbsp;million but would not release precise figures due to non-disclosure agreements.<ref name=noaa/><ref name=HPC>{{cite web|url=http://www.hpcwire.com/hpcwire/2011-10-11/gpus_will_morph_ornl_s_jaguar_into_20-petaflop_titan.html|title=GPUs Will Morph ORNL's Jaguar Into 20-Petaflop Titan|publisher=HPC Wire|date=October 11, 2011|accessdate=October 29, 2012|last=Feldman|first=Michael}}</ref> Throughout the full term of the contract with Cray Titan will cost $97&nbsp;million not including potential upgrades to the machine.<ref name=HPC/>


Titan was funded primarily by the US Department of Energy through ORNL. Funding was sufficient to purchase the CPUs but not all of the GPUs so the ] agreed to fund the remaining nodes in return for computing time.<ref name=noaa/><ref name=cost/> ORNL scientific computing chief Jeff Nichols noted that Titan cost approximately $60&nbsp;million upfront, of which the NOAA contribution was less than $10&nbsp;million, but precise figures were covered by non-disclosure agreements.<ref name=noaa/><ref name=HPC/> The full term of the contract with Cray included $97&nbsp;million, excluding potential upgrades.<ref name=HPC/>
Jaguar's internals were upgraded to Titan over the course of a year beginning October 9, 2011.<ref name="project timeline">{{cite web|title=Titan Project Timeline|url=http://www.olcf.ornl.gov/titan/system-configuration-timeline/|publisher=]|accessdate=December 18, 2012}}</ref><ref name=review>{{cite web|url=http://www.ornl.gov/info/ornlreview/v45_3_12/Review_v45n3.pdf|publisher=]|year=2012|accessdate=November 2, 2012|first1=Jennifer|last1=Brouner|first2=Morgan|last2=McCorkle|first3=Jim|last3=Pearce|first4=Leo|last4=Williams|title=ORNL Review Vol. 45}}</ref> Between October and December 96 of Jaguar's 200 cabinets containing ] ] (two 6-core CPUs per node) were upgraded with ] blades (one 16-core CPU per node) while the remainder of the machine was still available for processing.<ref name="project timeline" /> In December computation was moved to the 96 XK6 cabinets and the remaining 104 cabinets were upgraded to XK6.<ref name="project timeline"/> The system's interconnect (the network that allows the CPUs to communicate with each other) was updated and the ORNL's ESnet connection was upgraded to 100&nbsp;] to permit faster data transfer to other ], universities and research institutions.<ref name="project timeline" /><ref>{{cite web|title=Superfast Titan, Superfast Network|url=http://www.olcf.ornl.gov/2012/12/17/superfast-titan-superfast-network/|publisher=]|accessdate=December 18, 2012|date=December 17, 2012}}</ref> The system ] was doubled to 600&nbsp;] as the nodes were upgraded to XK6.<ref name=review /> 960 of the XK6 nodes (10 cabinets) were also fitted with a ] based Nvidia GPU as ] based GPUs were not yet available; these 960&nbsp;nodes were referred to as TitanDev and used to test code for Titan's full upgrade.<ref name="project timeline" /><ref name=review /> This first phase of the upgrade increased the peak performance of Jaguar to 3.3&nbsp;petaFLOPS although the computer was still called Jaguar.<ref name=review /> Beginning on September 13, 2012 ] K20X GPUs were fitted to Jaguar's XK6 compute blades but continued to use the same CPUs.<ref name="project timeline" /><ref name=PC>{{cite web|url=http://www.pcmag.com/article2/0,2817,2394515,00.asp|title=Cray's Titan Supercomputer for ORNL Could Be World's Fastest|publisher=]|first=Damon|last=Poeter|accessdate=October 29, 2012|date=October 11, 2011}}</ref><ref>{{cite web|last=Jones|first=Gregory Scott|title=Final Upgrade Underway|url=http://www.olcf.ornl.gov/2012/09/17/final-upgrade-underway/|publisher=Oak Ridge Leadership Computing Facility|accessdate=November 16, 2012|date=September 17, 2012}}</ref> In October the task was completed and the computer was renamed Titan, having remained "Jaguar" until this point.<ref name="project timeline" /> Titan will undergo acceptance testing until early 2013 and once completed it will be made available to researchers.<ref name="project timeline"/>

The yearlong conversion began October 9, 2011.<ref name="project timeline"/><ref name=review/> Between October and December, 96 of Jaguar's 200 cabinets, each containing 24&nbsp;] ] (two 6-core CPUs per node, four nodes per blade), were upgraded to ] blade (one 16-core CPU per node, four nodes per blade) while the remainder of the machine remained in use.<ref name="project timeline" /> In December, computation was moved to the 96 XK7 cabinets while the remaining 104 cabinets were upgraded to XK7 blades.<ref name="project timeline"/> ORNL's external ] connection was upgraded from 10&nbsp;] to 100&nbsp;Gbit/s and the system interconnect (the network over which CPUs communicate with each other) was updated.<ref name="project timeline" /><ref name=superfast/> The Seastar design used in Jaguar was upgraded to the Gemini interconnect used in Titan which connects the nodes into a direct 3D ] network.<ref name=gemini/> Gemini uses ] internally.<ref name=gemini/> The system ] was doubled to 584&nbsp;].<ref name=review /> 960 of the XK7 nodes (10&nbsp;cabinets) were fitted with a ] based GPU as ] GPUs were not then available; these 960&nbsp;nodes were referred to as TitanDev and used to test code.<ref name="project timeline" /><ref name=review /> This first phase of the upgrade increased the peak performance of Jaguar to 3.3&nbsp;petaFLOPS.<ref name=review /> Beginning on September 13, 2012, Nvidia K20X GPUs were fitted to all of Jaguar's XK7 compute blades, including the 960 TitanDev nodes.<ref name="project timeline" /><ref name=PC/><ref name=finalupgrade/> In October, the task was completed and the computer was finally renamed Titan.<ref name="project timeline" />

In March 2013, Nvidia launched the ], a consumer ] that uses the same GPU die as the K20X GPUs in Titan.<ref name=gtxtitan/> Titan underwent acceptance testing in early 2013 but only completed 92% of the tests, short of the required 95%.<ref name="project timeline"/><ref name=liveup/> The problem was discovered to be excess gold in the ] of the ]s' ] slots causing cracks in the motherboards' solder.<ref name=solder/> The cost of repair was borne by Cray and between 12 and 16 cabinets were repaired each week.<ref name=solder/> Throughout the repairs users were given access to the available CPUs.<ref name=solder/> On March 11, they gained access to 8,972&nbsp;GPUs.<ref name=gpuson/> ORNL announced on April 8 that the repairs were complete<ref name=repairsdone/> and acceptance test completion was announced on June 11, 2013.<ref name=accepted/>

Titan's hardware has a theoretical peak performance of 27&nbsp;] with "perfect" software.<ref name=ornlnamed/> On November 12, 2012, the TOP500 organization that ranks the world's supercomputers by ] performance, ranked Titan first at 17.59&nbsp;petaFLOPS, displacing ].<ref name=top500 /><ref name=bbcclocked/> Titan also ranked third on the ], the same 500 supercomputers ranked in terms of energy efficiency.<ref name=alsogreen/> In the June 2013 TOP500 ranking, Titan fell to second place behind ] and to twenty-ninth on the Green500 list.<ref name=tianhe2/><ref name=greenjune/> Titan did not re-test for the June 2013 ranking,<ref name=tianhe2/> because it would still have ranked second, at 27&nbsp;petaFLOPS.<ref name=tianhe/>


==Hardware== ==Hardware==
Titan uses the same building and 200 cabinets covering 404&nbsp;m<sup>2</sup> (4352&nbsp;sq&nbsp;ft) that Jaguar did, replacing the internals and upgrading networking facilities.<ref name=cnet>{{cite web|url=http://news.cnet.com/8301-11386_3-57541791-76/titan-supercomputer-debuts-for-open-scientific-research/|title=Titan supercomputer debuts for open scientific research|publisher=]|date=October 29, 2012|accessdate=October 29, 2012|first=Shara|last=Tibken}}</ref><ref name="olcf main">{{cite web|url=http://www.olcf.ornl.gov/titan/|title=Introducing Titan|publisher=]|accessdate=October 29, 2012}}</ref> Reusing the power and cooling systems already in place for Jaguar saved the lab approximately US $20 million.<ref>{{cite web|url=http://www.knoxnews.com/news/2012/oct/29/titans-ready-to-roll-ornl-supercomputer-may-no-1/|title=Titan's ready to roll; ORNL supercomputer may become world's No. 1|publisher=Knox News|date=October 29, 2012|accessdate=October 29, 2012|first=Frank|last=Munger}}</ref> Titan draws 8.2&nbsp;],<ref>{{cite web|title=Heterogeneous Systems Re-Claim Green500 List Dominance|url=http://www.green500.org/lists/green201211|publisher=]|date=November 14, 2012|accessdate=November 15, 2012}}</ref> 1.2&nbsp;MW more than Jaguar did, but it is almost ten times as fast in terms of ] calculations.<ref name=cnet/><ref name=anand>{{cite web|url=http://www.anandtech.com/show/6421/inside-the-titan-supercomputer-299k-amd-x86-cores-and-186k-nvidia-gpu-cores|title=Inside the Titan Supercomputer|publisher=]|first=Anand|last=Lal Shimpi|authorlink=Anand Lal Shimpi|page=1|date=October 31, 2012|accessdate=November 2, 2012}}</ref> Power is provided to each cabinet at 480&nbsp;] to use thinner cables than the US standard 208&nbsp;V, saving US&nbsp;$1&nbsp;million in copper.<ref name=anand /> In the event of a power failure, ] ]s power generators that can keep the networking and storage infrastructure running for up to 16&nbsp;seconds.<ref name=anandpower>{{cite web|url=http://www.youtube.com/watch?v=lPqvUWlIM7Y|title=Oak Ridge National Laboratory Tour - Backup Power|publisher=]|date=October 30, 2012|first1=Buddy|last1=Bland|authorlink2=Anand Lal Shimpi|first2=Anand|last2=Lal Shimpi|accessdate=November 2, 2012|format=]}}</ref> If power is not restored within 2&nbsp;seconds, diesel engines are started, taking approximately 7&nbsp;seconds, and assume the role of powering the generators indefinitely.<ref name=anandpower /> The flywheels and generators are designed only to keep the networking and storage components powered so that a reboot is much quicker, the generators are not capable of powering the processing infrastructure to continue simulations.<ref name=anandpower/> Titan's components are air-cooled with ]s, but the air is chilled before being pumped through the cabinets.<ref name=anandcool>{{cite web|url=http://www.youtube.com/watch?v=hruwUmd9NaE|title=Oak Ridge National Laboratory Tour - Cooling Requirements|publisher=]|date=October 30, 2012|first1=Buddy|last1=Bland|authorlink2=Anand Lal Shimpi|first2=Anand|last2=Lal Shimpi|accessdate=November 2, 2012|format=]}}</ref> The cooling system has a ] of 6600&nbsp;tons and works by cooling water to 5.5&nbsp;] (42&nbsp;]), which in turn chills the recirculated air.<ref name=anandcool /> Titan uses Jaguar's 200 cabinets, covering 404&nbsp;square&nbsp;meters (4,352&nbsp;ft<sup>2</sup>), with replaced internals and upgraded networking.<ref name=cnet/><ref name="olcf main"/> Reusing Jaguar's power and cooling systems saved approximately $20 million.<ref name=readytoroll/> Power is provided to each cabinet at ] 480&nbsp;]. This requires thinner cables than the US standard 208&nbsp;V, saving $1&nbsp;million in copper.<ref name=anand /> At its peak, Titan draws 8.2&nbsp;],<ref name=green500/> 1.2&nbsp;MW more than Jaguar, but runs almost ten times as fast in terms of ] calculations.<ref name=cnet/><ref name=anand/> In the event of a power failure, ] ] can keep the networking and storage infrastructure running for up to 16&nbsp;seconds.<ref name=anandpower/> After 2&nbsp;seconds without power, diesel generators fire up, taking approximately 7&nbsp;seconds to reach full power. They can provide power indefinitely.<ref name=anandpower /> The generators are designed only to keep the networking and storage components powered so that a reboot is much quicker; the generators are not capable of powering the processing infrastructure.<ref name=anandpower/>


Titan has 18,688&nbsp;nodes (4 nodes per blade, 24 blades per cabinet),<ref name="spots" /> each containing a ] ] ] CPU with 32&nbsp;GB of ] ] and an Nvidia Tesla K20X GPU with 6&nbsp;GB ] ECC memory.<ref name="olcf debut" /> There are a total of 299,008 processor cores, and a total of 693.6&nbsp;TiB of CPU and GPU RAM.<ref name="anand" />
Titan has 18,688 nodes (4 nodes per blade, 24 blades per cabinet),<ref>{{cite web|last=Morgan|first=Timothy Prickett|title=Oak Ridge changes Jaguar's spots from CPUs to GPUs|url=http://www.theregister.co.uk/2011/10/11/oak_ridge_cray_nvidia_titan/|publisher=]|accessdate=December 21, 2012|date=October 11, 2011}}</ref> each containing a ] ] CPU with 32&nbsp;GB of ] ] and an ] K20X GPU with 6&nbsp;GB ] ECC memory.<ref name="olcf debut">{{cite web|url=http://www.olcf.ornl.gov/wp-content/themes/olcf/titan/Titan_Debuts.pdf|title=ORNL Debuts Titan Supercomputer|publisher=]|accessdate=October 29, 2012}}</ref> The total number of processor cores is 299,&nbsp;008 and the total amount of RAM is over 710&nbsp;TB.<ref name=anand /> 10&nbsp;PB of storage (made up of 13,&nbsp;400 7200&nbsp;rpm 1&nbsp;TB ]s)<ref>{{cite web|last=Lal Shimpi|first=Anand|title=Titan's storage array|url=http://www.anandtech.com/Gallery/Album/2417#55|publisher=]|accessdate=December 18, 2012|authorlink=Anand Lal Shimpi|date=October 31, 2012}}</ref> is available with a transfer speed of 240&nbsp;GB/s.<ref name="olcf main" /><ref name=anand /> The next storage upgrade is due in 2013, it will up the total storage to between 20 and 30&nbsp;PB with a transfer speed of approximately 1&nbsp;TB/s.<ref name=anand /><ref>{{cite web|title=TITAN OVERVIEW|url=http://www.olcf.ornl.gov/titan/titan-overview/|publisher=Oak Ridge Leadership Computing Facility|accessdate=December 18, 2012}}</ref> Titan runs the ], a full version of ] on the login nodes but a scaled down, more efficient version on the compute nodes.<ref>{{cite web|title=Titan System Overview|url=http://www.olcf.ornl.gov/kb_articles/titan-system-overview/|publisher=]|accessdate=December 21, 2012}}</ref> GPUs were selected for their vastly higher parallel processing efficiency over CPUs.<ref name="olcf debut" /> Although the GPUs have a slower ] than the CPUs, each GPU contains 2,&nbsp;688 ] cores at 732&nbsp;],<ref>{{cite web|last=Smith|first=Ryan|title=NVIDIA Launches Tesla K20 & K20X: GK110 Arrives At Last|url=http://www.anandtech.com/show/6446/nvidia-launches-tesla-k20-k20x-gk110-arrives-at-last|publisher=]|accessdate=December 21, 2012|date=November 12, 2012}}</ref> resulting in a faster overall system.<ref name="olcf main" /><ref>{{cite web|url=http://www.hpcwire.com/hpcwire/2012-10-29/titan_sets_high-water_mark_for_gpu_supercomputing.html|title=Titan Sets High Water Mark for GPU Supercomputing|publisher=HPC Wire|date=October 29, 2012|accessdate=October 30, 2012|first=Michael|last=Feldman}}</ref> Consequently, the CPUs cores are used to allocate tasks to the GPUs rather than for directly processing the data as in previous supercomputers for well optimised codes.<ref name="olcf debut" />


Initially, Titan used Jaguar's 10&nbsp;PB of ] storage with a transfer speed of 240&nbsp;GB/s,<ref name=anand /><ref name=storage/> but in April 2013, the storage was upgraded to 40&nbsp;PB with a transfer rate of 1.4&nbsp;TB/s.<ref name=storage2/> GPUs were selected for their vastly higher parallel processing efficiency over CPUs.<ref name="olcf debut" /> Although the GPUs have a slower ] than the CPUs, each GPU contains 2,688 ] cores at 732&nbsp;],<ref name=teslalaunch/> resulting in a faster overall system.<ref name="olcf main" /><ref name=highwater/> Consequently, the CPUs' cores are used to allocate tasks to the GPUs rather than directly processing the data as in conventional supercomputers.<ref name="olcf debut" />
Titan's hardware has a theoretical peak performance of 27 ] with perfectly optimised software.<ref>{{cite web|last=Jones|first=Gregory Scott|title=ORNL Supercomputer Named World’s Most Powerful|url=http://www.olcf.ornl.gov/2012/11/12/ornl-supercomputer-named-worlds-most-powerful/|publisher=]|accessdate=December 14, 2012|date=November 12, 2012}}</ref> On November 12, 2012 the ] organisation that ranks the worlds' supercomputers by their ] performance announced that Titan was ranked first at 17.59 ], displacing ].<ref name=top500 /><ref>{{cite web|url=http://www.bbc.co.uk/news/technology-20272810/|title=US Titan supercomputer clocked as world's fastest|publisher=BBC|date=November 12, 2012|accessdate=November 12, 2012|first=|last=}}</ref> Titan was also ranked third on the ], the same 500 supercomputers but re-ordered in terms of energy efficiency.<ref>{{cite web|url=https://www.olcf.ornl.gov/2012/11/14/titan-is-also-a-green-powerhouse/|publisher=Oak Ridge Leadership Computing Facility|date=November 14, 2012|first=Leo|last=Williams|accessdate=November 15, 2012|title=Titan is Also a Green Powerhouse}}</ref>


Titan runs the ], a full version of ] on the login nodes that users directly access, but a smaller, more efficient version on the compute nodes.<ref name="overview" />
==Research projects==
]'s core. This image was rendered on ] but the project will continue with greater detail on Titan.]]
Although Titan is available for use by any project, the requests for use exceeded the computing time available, so selection criteria were drawn up. In 2009, the Oak Ridge Leadership Computing Facility (OLCF) considered fifty applications for first use of the supercomputer, but narrowed it down to six successful candidates chosen not only for the importance of the research, but for their ability to fully utilise the computing power of the hybrid system.<ref name="olcf main" /><ref name="built for science">{{cite web|url=http://www.olcf.ornl.gov/wp-content/themes/olcf/titan/Titan_BuiltForScience.pdf|title=TITAN: Built for Science|publisher=]|accessdate=October 29, 2012}}</ref> The code of projects had to be modified to suit the GPU processing of Titan, but the code was required to still be capable of running on CPU-based systems so that the projects were not solely dependent on Titan.<ref name="built for science" /> OLCF formed the Center for Accelerated Application Readiness (CAAR) to aid researchers in modifying their code for Titan and holds developer workshops at Nvidia headquarters to educate users about the architecture, compilers and applications on Titan and other supercomputers.<ref name=moving>{{cite web|last=Williams|first=Leo|title=Preparing users for Titan|url=http://www.ornl.gov/info/ornlreview/v45_3_12/article03a.shtml|publisher=]|accessdate=November 19, 2012}}</ref><ref>{{cite web|last=Rumsey|first=Jeremy|title=Titan Trainers Take Road Trip|url=http://www.olcf.ornl.gov/2012/12/17/titan-trainers-take-road-trip/|publisher=]|accessdate=December 18, 2012|date=December 17, 2012}}</ref> CAAR has been working on ]s with Nvidia and code vendors to integrate directives into the programming languages for GPUs.<ref name=moving/> Researchers can then express parallelism in their code without learning a new programming language, typically ], ] or ], and the compiler can express it to the GPUs.<ref name=moving/> Dr. Bronson Messer, a computational ], said of the task: "...an application using Titan to the utmost must also find a way to keep the GPU busy, remembering all the while that the GPU is fast, but less flexible than the CPU."<ref name=moving/> Some projects found that the changes increased efficiency of their code on non-GPU machines; the performance of ''Denovo'' doubled on CPU-based machines.<ref name="built for science" />


Titan's components are air-cooled by ]s, but the air is chilled before being pumped through the cabinets.<ref name=anandcool/> Fan noise is so loud that hearing protection is required for people spending more than 15 minutes in the machine room.<ref name=bbc/> The system has a cooling capacity of 23.2 MW (6600 tons) and works by chilling water to 5.5&nbsp;°C (42&nbsp;°F), which in turn cools recirculated air.<ref name=anandcool/>
The six initial projects to use Titan include ''S3D'', a project that models fine grain physics surrounding combustion aiming to improve the efficiency of diesel and biofuel engines. In 2009, they produced the first fully resolved simulation of autoigniting hydrocarbon flames relevant to the efficiency of ] ]s using Jaguar.<ref name="built for science" /> The ''WL-LSMS'' project simulates the interactions between electrons and atoms in magnetic materials at temperatures other than ]. An earlier version of the code was the first to perform at greater than one petaFLOPS on Jaguar.<ref name="built for science" /> ''Denovo'' simulates nuclear reactions with the aim of improving the efficiency and reducing the waste of ]s.<ref name="olcf main" /> The performance of ''Denovo'' on conventional CPU-based machines doubled after the tweaks for Titan and performs 3.5 faster on Titan than it did on Jaguar.<ref name="built for science" /><ref>{{cite web|title=Nuclear Energy - Supercomputer speeds path forward|url=http://www.casl.gov/highlights/supercomputer.shtml|publisher=Consortium for Advanced Simulation of LWRs|accessdate=December 14, 2012}}</ref> ''Large-scale Atomic/Molecular Massively Parallel Simulator'' (''LAMMPS'') is a ] code that simulates particles across a range of scales, from atomic to ], to improve materials science with potential applications in ]s, ]s and ]s.<ref>{{cite web|url=http://lammps.sandia.gov/|title=LAMMPS Molecular Dynamics Simulator|publisher=]|accessdate=October 29, 2012|first=Sergey|last=Zybin}}</ref> ''CAM-SE'' is a combination of two codes: ''Community Atmosphere Model'', a global atmosphere model, and ''High Order Method Modeling Environment'', a code that solves fluid and thermodynamic equations. ''CAM-SE'' will allow greater accuracy in climate simulations.<ref name="built for science" /> ''Non-Equilibrium Radiation Diffusion'' (''NRDF'') plots non-charged particles through ]e with potential applications in ], ], ], nuclear reactors, energy storage and combustion.<ref name="built for science" />


Researchers also have access to EVEREST (Exploratory Visualization Environment for Research and Technology) to better understand the data that Titan outputs. EVEREST is a ] room with a 10 by 3&nbsp;meter (33 by 10&nbsp;ft) screen and a smaller, secondary screen. The screens are 37 and 33&nbsp;]s respectively with ] capability.<ref name="everest" />
The amount of code alteration required to run on the GPUs varies by project. According to Dr. Messer of the ''NRDF'' project, only a small percentage of his code is for the GPUs because the calculations are relatively simple but processed repeatedly and in parallel.<ref name=anandsoftware>{{cite web|url=http://www.anandtech.com/show/6421/inside-the-titan-supercomputer-299k-amd-x86-cores-and-186k-nvidia-gpu-cores/3|title=Inside the Titan Supercomputer|page=3|publisher=]|first=Anand|last=Lal Shimpi|authorlink=Anand Lal Shimpi|date=October 31, 2012|accessdate=November 15, 2012}}</ref> ''NRDF'' is written in ], a version of normal ] with CUDA extensions for the GPUs.<ref name=anandsoftware/> Dr. Messer's research requires hundreds of ]s to track the energy, angle, angle of scatter and type of each ] modeled in a star going ], resulting in millions of individual equations.<ref name=messervid>{{cite web|last=Messer|first=Bronson|title=Using Titan to Model Supernovae|url=http://www.youtube.com/watch?&v=-BY9K12TbUY|publisher=]|accessdate=November 15, 2012|format=]|date=October 30, 2012}}</ref> The code was named ''Chimera'' after the ] because it has three "heads": the first simulates the hydrodynamics of ], the second simulates radiation transport and the third simulates ].<ref name=messervid/> The third "head" is the first to run on the GPUs as the nuclear burning can most easily be simulated by GPU architecture although the other aspects of the code will be modified in time.<ref name=messervid/> Currently the project models 14 or 15 ] but if the GPUs provide good acceleration Dr. Messer anticipates up to 200 species could be simulated allowing far greater precision when comparing to empirical observation.<ref name=messervid/>


==Projects==
''VERA'' is a ] simulation written at the Consortium for Advanced Simulation of Light Water Reactors (CASL) on Jaguar. ''VERA'' allows engineers to monitor the performance and status of any part of a reactor core throughout the lifetime of the reactor to identify points of interest.<ref name=VERA>{{cite web|last=Pearce|first=Jim|title=VERA analyzes nuclear reactor designs in unprecedented detail|url=http://www.ornl.gov/info/ornlreview/v45_3_12/article05.shtml|publisher=]|accessdate=18 December 2012}}</ref> Although not one of the first six projects, ''VERA'' will be run on Titan having been optimised with assistance from CAAR and tested on TitanDev. Computer scientist Tom Evans found that the adaption to Titan's hybrid architecture was of greater difficulty than between previous CPU based supercomputers, despite this he aims to simulate an entire reactor fuel cycle, an eighteen to thirty-six month process, in one week on Titan.<ref name=VERA/>
In 2009, the Oak Ridge Leadership Computing Facility that manages Titan narrowed the fifty applications for first use of the supercomputer down to six "vanguard" codes chosen for the importance of the research and for their ability to fully utilize the system.<ref name="olcf main" /><ref name="built for science" /> The six vanguard projects to use Titan were:
* ''S3D'', a project that models the molecular physics of combustion, aims to improve the efficiency of diesel and ] engines. In 2009, using Jaguar, it produced the first fully resolved simulation of autoigniting ] flames relevant to the efficiency of ] ]s.<ref name="built for science" />
* ''WL-LSMS'' simulates the interactions between electrons and atoms in magnetic materials at temperatures other than ]. An earlier version of the code was the first to perform at greater than one petaFLOPS on Jaguar.<ref name="built for science" />
* ''Denovo'' simulates ]s with the aim of improving the efficiency and reducing the waste of ]s.<ref name="olcf main" /> The performance of ''Denovo'' on conventional CPU-based machines doubled after the tweaks for Titan and it performs 3.5 times faster on Titan than it did on Jaguar.<ref name="built for science" /><ref name=nuclear/>
* '']'' (''LAMMPS'') is a ] code that simulates particles across a range of scales, from ] to ], to improve materials science with potential applications in ], ] and ] development.<ref name=LAAMPS/>
* ''CAM-SE'' is a combination of two codes: ''Community Atmosphere Model'', a global atmosphere model, and ''High Order Method Modeling Environment'', a code that solves fluid and thermodynamic equations. ''CAM-SE'' will allow greater accuracy in climate simulations.<ref name="built for science" />
* ''Non-Equilibrium Radiation Diffusion'' (''NRDF'') plots non-charged particles through ]e with potential applications in ], ], ], nuclear reactors, energy storage and combustion.<ref name="built for science" /> Its Chimera code uses hundreds of ]s to track the energy, angle, angle of scatter and type of each ] modeled in a star going ], resulting in millions of individual equations.<ref name=messervid/> The code was named ''Chimera'' after the ] because it has three "heads": the first simulates the hydrodynamics of ], the second simulates ] and the third simulates ].<ref name=messervid/>
* ''Bonsai'' is a gravitational tree code for ]. It has been used for the 2014 Gordon Bell prize nomination for simulating the Milky Way Galaxy on a star by star basis, with 200 billion stars. In this application the computer reached a sustained speed of 24.773 petaFlops.<ref name="bedorf" />
*''VERA'' is a ] simulation written at the Consortium for Advanced Simulation of Light Water Reactors (CASL) on Jaguar. ''VERA'' allows engineers to monitor the performance and status of any part of a ] throughout the lifetime of the reactor to identify points of interest.<ref name=VERA/> Although not one of the first six projects, ''VERA'' was planned to run on Titan after optimization with assistance from CAAR and testing on TitanDev. Computer scientist Tom Evans found that the adaption to Titan's hybrid architecture was more difficult than to previous CPU-based supercomputers. He aimed to simulate an entire ], an eighteen to thirty-six month-long process, in one week on Titan.<ref name=VERA/>


In 2013 thirty-one programs were planned to run on Titan, typically four or five at any one time.<ref name=bbc/><ref name=incite/>
==See also==

*]
==Code modifications==
{{see also|General-purpose computing on graphics processing units{{!}}GPGPU}}

The code of many projects has to be modified to suit the GPU processing of Titan, but each code is required to be executable on CPU-based systems so that projects do not become solely dependent on Titan.<ref name="built for science" /> OLCF formed the Center for Accelerated Application Readiness (CAAR) to aid with the adaptation process. It holds developer workshops at Nvidia headquarters to educate users about the architecture, compilers and applications on Titan.<ref name="moving" /><ref name="trainers" /> CAAR has been working on ]s with Nvidia and code vendors to integrate ]s for GPUs into their programming languages.<ref name="moving" /> Researchers can thus express parallelism in their code with their existing programming language, typically ], ] or ], and the compiler can express it to the GPUs.<ref name="moving" /> Dr. Bronson Messer, a computational ], said of the task: "an application using Titan to the utmost must also find a way to keep the GPU busy, remembering all the while that the GPU is fast, but less flexible than the CPU."<ref name="moving" /> ] is used to prioritize jobs to nodes to keep utilization high; it improved efficiency from 70% to approximately 95% in the tested software.<ref name="moab" /><ref name="cloud" /> Some projects found that the changes increased efficiency of their code on non-GPU machines; the performance of ''Denovo'' doubled on CPU-based machines.<ref name="built for science" />

The amount of code alteration required to run on the GPUs varies by project. According to Dr. Messer of ''NRDF'', only a small percentage of his code runs on GPUs because the calculations are relatively simple but processed repeatedly and in parallel.<ref name=anandsoftware/> ''NRDF'' is written in ], a version of ] with CUDA extensions for the GPUs.<ref name=anandsoftware/> Chimera's third "head" was the first to run on the GPUs as the nuclear burning could most easily be simulated by GPU architecture. Other aspects of the code were planned to be modified in time.<ref name=messervid/> On Jaguar, the project modeled 14 or 15 ] but Messer anticipated simulating up to 200 species, allowing far greater precision when comparing the simulation to empirical observation.<ref name=messervid/>

== See also ==
* ] – OLCF-2
* ] – OLCF-4
* ]


==References== ==References==
{{reflist|30em|refs=
{{Reflist|2}}
<ref name=top500>{{cite web|title=Oak Ridge Claims No. 1 Position on Latest TOP500 List with Titan|url=http://www.top500.org/blog/lists/2012/11/press-release/|publisher=TOP500|access-date=November 15, 2012|date=November 12, 2012|archive-url=https://web.archive.org/web/20130121075914/http://top500.org/blog/lists/2012/11/press-release/|archive-date=January 21, 2013}}</ref>

<ref name=jag>{{cite web|title=Jaguar: Oak ridge National Laboratory|url=http://www.top500.org/featured/systems/jaguar-oak-ridge-national-laboratory/|publisher=TOP500|access-date=December 18, 2012|archive-url=https://web.archive.org/web/20130317002624/http://www.top500.org/featured/systems/jaguar-oak-ridge-national-laboratory/|archive-date=March 17, 2013}}</ref>

<ref name=jag500>{{cite web|title=TOP500 List November 2011|url=http://www.top500.org/lists/2011/11/|publisher=TOP500|access-date=December 18, 2012|archive-url=https://web.archive.org/web/20130121124148/http://www.top500.org/lists/2011/11/|archive-date=January 21, 2013}}</ref>

<ref name=jackwells>{{cite web|title=Discussing the ORNL Titan Supercomputer with ORNL's Jack Wells.|url=http://theexascalereport.com/content/2012/discussing-ornl-titan-supercomputer-ornl%E2%80%99s-jack-wells|publisher=The Exascale Report|access-date=December 19, 2012|date=November 2012|archive-url=https://web.archive.org/web/20130525195442/http://theexascalereport.com/content/2012/discussing-ornl-titan-supercomputer-ornl%E2%80%99s-jack-wells|url-status=dead|archive-date=May 25, 2013}}</ref>

<ref name=wheredowego>{{cite web|last=Bland|first=Buddy|title=Where do we go from here?|publisher=]|url=http://computing.ornl.gov/SC10/documents/SC10_Booth_Talk_Bland.pdf|access-date=December 18, 2012|date=November 16, 2010|archive-url=https://web.archive.org/web/20120303035245/http://computing.ornl.gov/SC10/documents/SC10_Booth_Talk_Bland.pdf|archive-date=March 3, 2012}}</ref>

<ref name=gaga>{{cite web|last=Morgan|first=Timothy Prickett|work=]|title=Oak Ridge goes gaga for Nvidia GPUs|url=https://www.theregister.co.uk/2009/10/01/oak_ridge_fermi/|access-date=December 19, 2012|date=October 1, 2009|archive-url=https://web.archive.org/web/20121109040239/https://www.theregister.co.uk/2009/10/01/oak_ridge_fermi/|archive-date=November 9, 2012}}</ref>

<ref name=contract>{{cite web|last=Levy|first=Dawn|title=ORNL awards contract to Cray for Titan supercomputer|url=http://www.ornl.gov/info/press_releases/get_press_release.cfm?ReleaseNumber=mr20111011-00|publisher=Oak Ridge National Laboratory|access-date=December 19, 2012|date=October 11, 2011|archive-url=https://web.archive.org/web/20130226230130/http://www.ornl.gov/info/press_releases/get_press_release.cfm?ReleaseNumber=mr20111011-00|archive-date=February 26, 2013}}</ref>

<ref name=titanic>{{cite web|last=Munger|first=Frank|url=http://www.knoxnews.com/news/2011/mar/07/oak-ridge-lab-to-add-titanic-supercomputer/|title=Oak Ridge lab to add titanic supercomputer|publisher=Knox News|access-date=December 19, 2012|date=March 7, 2011|archive-url=https://web.archive.org/web/20120704072926/http://www.knoxnews.com/news/2011/mar/07/oak-ridge-lab-to-add-titanic-supercomputer/|archive-date=July 4, 2012}}</ref>

<ref name=noaa>{{cite web|last=Munger|first=Frank|title=The ORNL and NOAA relationship|url=http://blogs.knoxnews.com/munger/2012/11/the-ornl-and-noaa-relationship.html|publisher=Knox News|access-date=December 20, 2012|date=November 26, 2012|archive-url=https://web.archive.org/web/20130522193925/http://blogs.knoxnews.com/munger/2012/11/the-ornl-and-noaa-relationship.html|url-status=dead|archive-date=May 22, 2013}}</ref>

<ref name=cost>{{cite web|last=Munger|first=Frank|title=The cost of Titan|url=http://blogs.knoxnews.com/munger/2012/11/the-cost-of-titan.html|publisher=Knox News|access-date=December 20, 2012|date=November 18, 2012|archive-url=https://web.archive.org/web/20130522190323/http://blogs.knoxnews.com/munger/2012/11/the-cost-of-titan.html|url-status=dead|archive-date=May 22, 2013}}</ref>

<ref name=HPC>{{cite web|url=http://www.hpcwire.com/hpcwire/2011-10-11/gpus_will_morph_ornl_s_jaguar_into_20-petaflop_titan.html|title=GPUs Will Morph ORNL's Jaguar Into 20-Petaflop Titan|work=HPC Wire|date=October 11, 2011|access-date=October 29, 2012|last=Feldman|first=Michael|archive-url=https://web.archive.org/web/20120727053123/http://www.hpcwire.com/hpcwire/2011-10-11/gpus_will_morph_ornl_s_jaguar_into_20-petaflop_titan.html|archive-date=July 27, 2012}}</ref>

<ref name="project timeline">{{cite web|title=Titan Project Timeline|url=http://www.olcf.ornl.gov/titan/system-configuration-timeline/|publisher=Oak Ridge Leadership Computing Facility|access-date=December 18, 2012|archive-url=https://web.archive.org/web/20120618110104/http://www.olcf.ornl.gov/titan/system-configuration-timeline|archive-date=June 18, 2012}}</ref>

<ref name=review>{{cite web|url=http://www.ornl.gov/info/ornlreview/v45_3_12/Review_v45n3.pdf|publisher=Oak Ridge National Laboratory|year=2012|access-date=November 2, 2012|first1=Jennifer|last1=Brouner|first2=Morgan|last2=McCorkle|first3=Jim|last3=Pearce|first4=Leo|last4=Williams|title=ORNL Review Vol. 45|archive-url=https://web.archive.org/web/20130304012345/http://www.ornl.gov/info/ornlreview/v45_3_12/Review_v45n3.pdf|archive-date=March 4, 2013}}</ref>

<ref name=superfast>{{cite web|title=Superfast Titan, Superfast Network|url=http://www.olcf.ornl.gov/2012/12/17/superfast-titan-superfast-network/|publisher=Oak Ridge Leadership Computing Facility|access-date=December 18, 2012|date=December 17, 2012|archive-url=https://web.archive.org/web/20130326053150/https://www.olcf.ornl.gov/2012/12/17/superfast-titan-superfast-network/|url-status=live|archive-date=March 26, 2013}}</ref>

<ref name=PC>{{cite web|url=https://www.pcmag.com/article2/0,2817,2394515,00.asp|title=Cray's Titan Supercomputer for ORNL Could Be World's Fastest|work=]|first=Damon|last=Poeter|access-date=October 29, 2012|date=October 11, 2011|archive-url=https://web.archive.org/web/20120605020152/http://www.pcmag.com/article2/0,2817,2394515,00.asp|archive-date=June 5, 2012}}</ref>

<ref name=finalupgrade>{{cite web|last=Jones|first=Gregory Scott|title=Final Upgrade Underway|url=http://www.olcf.ornl.gov/2012/09/17/final-upgrade-underway/|publisher=Oak Ridge Leadership Computing Facility|access-date=November 16, 2012|date=September 17, 2012|archive-url=https://web.archive.org/web/20130326070723/https://www.olcf.ornl.gov/2012/09/17/final-upgrade-underway/|url-status=live|archive-date=March 26, 2013}}</ref>

<ref name=cnet>{{cite web|url=http://news.cnet.com/8301-11386_3-57541791-76/titan-supercomputer-debuts-for-open-scientific-research/|title=Titan supercomputer debuts for open scientific research|website=]|date=October 29, 2012|access-date=October 29, 2012|first=Shara|last=Tibken|archive-url=https://web.archive.org/web/20121215071905/http://news.cnet.com/8301-11386_3-57541791-76/titan-supercomputer-debuts-for-open-scientific-research/|archive-date=December 15, 2012}}</ref>

<ref name="olcf main">{{cite web|url=http://www.olcf.ornl.gov/titan/|title=Introducing Titan|publisher=Oak Ridge Leadership Computing Facility|access-date=October 29, 2012|archive-url=https://web.archive.org/web/20130222153725/http://www.olcf.ornl.gov/titan|archive-date=February 22, 2013}}</ref>

<ref name=readytoroll>{{cite web|url=http://www.knoxnews.com/news/2012/oct/29/titans-ready-to-roll-ornl-supercomputer-may-no-1/|archive-url=https://web.archive.org/web/20130705030937/http://www.knoxnews.com/news/2012/oct/29/titans-ready-to-roll-ornl-supercomputer-may-no-1/|archive-date=July 5, 2013|url-status=dead|title=Titan's ready to roll; ORNL supercomputer may become world's No. 1|publisher=Knox News|date=October 29, 2012|access-date=October 29, 2012|first=Frank|last=Munger}}</ref>

<ref name=green500>{{cite web|title=Heterogeneous Systems Re-Claim Green500 List Dominance|url=http://www.green500.org/lists/green201211|publisher=]|date=November 14, 2012|access-date=November 15, 2012|archive-date=February 5, 2013|archive-url=https://web.archive.org/web/20130205205421/http://www.green500.org/lists/green201211}}</ref>

<ref name=anand>{{cite web|url=http://www.anandtech.com/show/6421/inside-the-titan-supercomputer-299k-amd-x86-cores-and-186k-nvidia-gpu-cores|title=Inside the Titan Supercomputer|publisher=Anandtech|first=Anand|last=Lal Shimpi|author-link=Anand Lal Shimpi|page=1|date=October 31, 2012|access-date=November 2, 2012|archive-date=January 25, 2013|archive-url=https://web.archive.org/web/20130125142636/http://www.anandtech.com/show/6421/inside-the-titan-supercomputer-299k-amd-x86-cores-and-186k-nvidia-gpu-cores}}</ref>

<ref name=anandpower>{{cite web|url=https://www.youtube.com/watch?v=lPqvUWlIM7Y|title=Oak Ridge National Laboratory Tour – Backup Power|publisher=Anandtech|date=October 30, 2012|first1=Buddy|last1=Bland|first2=Anand|last2=Lal Shimpi|access-date=November 2, 2012|format=Youtube}}</ref>

<ref name=anandcool>{{cite web|url=https://www.youtube.com/watch?v=hruwUmd9NaE|title=Oak Ridge National Laboratory Tour – Cooling Requirements|publisher=Anandtech|date=October 30, 2012|first1=Buddy|last1=Bland|first2=Anand|last2=Lal Shimpi|access-date=November 2, 2012|format=Youtube}}</ref>

<ref name=incite>{{cite web|title=2013 INCITE Awards|url=http://www.doeleadershipcomputing.org/awards/2013INCITEFactSheets.pdf|publisher=]|access-date=January 17, 2013|archive-url=https://web.archive.org/web/20121029121024/http://www.doeleadershipcomputing.org/awards/2013INCITEFactSheets.pdf|url-status=dead|archive-date=October 29, 2012}}</ref>

<ref name=bbc>{{cite web|last=Pavlus|first=John|title=Building Titan: The 'world's fastest' supercomputer|url=http://www.bbc.com/future/story/20121026-a-supercomputing-titan|publisher=]|access-date=January 8, 2013|date=October 29, 2012|archive-url=https://web.archive.org/web/20130130150834/http://www.bbc.com/future/story/20121026-a-supercomputing-titan|archive-date=January 30, 2013 }}</ref>

<ref name=spots>{{cite web|last=Morgan|first=Timothy Prickett|title=Oak Ridge changes Jaguar's spots from CPUs to GPUs|url=https://www.theregister.co.uk/2011/10/11/oak_ridge_cray_nvidia_titan/|work=]|access-date=December 21, 2012|date=October 11, 2011|archive-date=October 15, 2012|archive-url=https://web.archive.org/web/20121015054416/https://www.theregister.co.uk/2011/10/11/oak_ridge_cray_nvidia_titan/}}</ref>

<ref name="olcf debut">{{cite web|url=http://www.olcf.ornl.gov/wp-content/themes/olcf/titan/Titan_Debuts.pdf|title=ORNL Debuts Titan Supercomputer|publisher=Oak Ridge Leadership Computing Facility|access-date=October 29, 2012|archive-url=https://web.archive.org/web/20130226194137/http://www.olcf.ornl.gov/wp-content/themes/olcf/titan/Titan_Debuts.pdf|archive-date=February 26, 2013}}</ref>

<ref name=storage>{{cite web|last=Lal Shimpi|first=Anand|title=Titan's storage array|url=http://www.anandtech.com/Gallery/Album/2417#55|publisher=Anandtech|access-date=December 18, 2012|date=October 31, 2012|archive-url=https://web.archive.org/web/20130406225450/http://www.anandtech.com/Gallery/Album/2417|url-status=live|archive-date=April 6, 2013}}</ref>

<ref name=overview>{{cite web|title=Titan System Overview|url=http://www.olcf.ornl.gov/kb_articles/titan-system-overview/|publisher=Oak Ridge Leadership Computing Facility|access-date=December 21, 2012|archive-date=February 17, 2013|url-status=dead|archive-url=https://web.archive.org/web/20130217001423/https://www.olcf.ornl.gov/kb_articles/titan-system-overview/}}</ref>

<ref name=teslalaunch>{{cite web|last=Smith|first=Ryan|title=NVIDIA Launches Tesla K20 & K20X: GK110 Arrives At Last|url=http://www.anandtech.com/show/6446/nvidia-launches-tesla-k20-k20x-gk110-arrives-at-last|publisher=Anandtech|access-date=December 21, 2012|date=November 12, 2012|archive-url=https://web.archive.org/web/20130124155802/http://www.anandtech.com/show/6446/nvidia-launches-tesla-k20-k20x-gk110-arrives-at-last|archive-date=January 24, 2013}}</ref>

<ref name=highwater>{{cite web|url=http://www.hpcwire.com/hpcwire/2012-10-29/titan_sets_high-water_mark_for_gpu_supercomputing.html|title=Titan Sets High Water Mark for GPU Supercomputing|work=HPC Wire|date=October 29, 2012|access-date=October 30, 2012|first=Michael|last=Feldman|archive-date=November 5, 2012|url-status=dead|archive-url=https://web.archive.org/web/20121105052325/http://www.hpcwire.com/hpcwire/2012-10-29/titan_sets_high-water_mark_for_gpu_supercomputing.html}}</ref>

<ref name=ornlnamed>{{cite web|last=Jones|first=Gregory Scott|title=ORNL Supercomputer Named World's Most Powerful|url=http://www.olcf.ornl.gov/2012/11/12/ornl-supercomputer-named-worlds-most-powerful/|publisher=Oak Ridge National Laboratory|access-date=December 14, 2012|date=November 12, 2012|archive-date=February 22, 2013|archive-url=https://web.archive.org/web/20130222134206/http://www.olcf.ornl.gov/2012/11/12/ornl-supercomputer-named-worlds-most-powerful/}}</ref>

<ref name=bbcclocked>{{cite web|url=https://www.bbc.co.uk/news/technology-20272810|title=US Titan supercomputer clocked as world's fastest|publisher=BBC|date=November 12, 2012|access-date=November 12, 2012|archive-date=February 3, 2013|archive-url=https://web.archive.org/web/20130203134252/http://www.bbc.co.uk/news/technology-20272810}}</ref>

<ref name=alsogreen>{{cite web|url=https://www.olcf.ornl.gov/2012/11/14/titan-is-also-a-green-powerhouse/|publisher=Oak Ridge Leadership Computing Facility|date=November 14, 2012|first=Leo|last=Williams|access-date=November 15, 2012|title=Titan is Also a Green Powerhouse|archive-date=February 16, 2013|archive-url=https://web.archive.org/web/20130216033517/https://www.olcf.ornl.gov/2012/11/14/titan-is-also-a-green-powerhouse/}}</ref>

<ref name=everest>{{cite web|last=Munger|first=Frank|title=ORNL visualization lab gets $2.5M makeover, adds 3D|url=http://www.knoxnews.com/news/2013/jan/01/ornl-visualization-lab-gets-25m-makeover-adds-3d/|publisher=Knox News|access-date=March 30, 2019|date=January 1, 2013|archive-url=https://web.archive.org/web/20130524115041/http://www.knoxnews.com/news/2013/jan/01/ornl-visualization-lab-gets-25m-makeover-adds-3d/|url-status=dead|archive-date=May 24, 2013}}</ref>

<ref name="built for science">{{cite web|url=http://www.olcf.ornl.gov/wp-content/themes/olcf/titan/Titan_BuiltForScience.pdf|title=TITAN: Built for Science|publisher=Oak Ridge Leadership Computing Facility|access-date=October 29, 2012|archive-url=https://web.archive.org/web/20130226173844/http://www.olcf.ornl.gov/wp-content/themes/olcf/titan/Titan_BuiltForScience.pdf|archive-date=February 26, 2013}}</ref>

<ref name=moab>{{cite web|title=Supercomputing Leaders Choose Adaptive Computing to Complement Latest HPC Systems|url=http://eon.businesswire.com/news/eon/20130130005098/en/Beacon/University-of-Tennessee-National-Institute/Titan-Supercomputer|work=]|archive-date=May 18, 2013|url-status=dead|archive-url=https://web.archive.org/web/20130518190945/http://eon.businesswire.com/news/eon/20130130005098/en/Beacon/University-of-Tennessee-National-Institute/Titan-Supercomputer|access-date=January 31, 2013|date=January 30, 2013}}</ref>

<ref name=cloud>{{cite web|last=DuBois|first=Shelley|title=The next revolution in cloud computing|url=http://tech.fortune.cnn.com/2013/01/30/the-next-revolution-in-cloud-computing/|work=]|access-date=January 31, 2013|date=January 30, 2013|archive-date=April 2, 2013|url-status=dead|archive-url=https://web.archive.org/web/20130402234835/http://tech.fortune.cnn.com/2013/01/30/the-next-revolution-in-cloud-computing/}}</ref>

<ref name=moving>{{cite web|last=Williams|first=Leo|title=Preparing users for Titan|url=http://www.ornl.gov/info/ornlreview/v45_3_12/article03a.shtml|publisher=Oak Ridge National Laboratory|access-date=November 19, 2012|archive-date=March 1, 2013|archive-url=https://web.archive.org/web/20130301073622/http://www.ornl.gov/info/ornlreview/v45_3_12/article03a.shtml}}</ref>

<ref name=trainers>{{cite web|last=Rumsey|first=Jeremy|title=Titan Trainers Take Road Trip|url=http://www.olcf.ornl.gov/2012/12/17/titan-trainers-take-road-trip/|publisher=Oak Ridge Leadership Computing Facility|access-date=December 18, 2012|date=December 17, 2012|archive-date=March 26, 2013|url-status=live|archive-url=https://web.archive.org/web/20130326080625/https://www.olcf.ornl.gov/2012/12/17/titan-trainers-take-road-trip/}}</ref>

<ref name=nuclear>{{cite web|title=Nuclear Energy – Supercomputer speeds path forward|url=http://www.casl.gov/highlights/supercomputer.shtml|publisher=Consortium for Advanced Simulation of LWRs|access-date=December 14, 2012|archive-date=February 14, 2013|archive-url=https://web.archive.org/web/20130214225507/http://www.casl.gov/highlights/supercomputer.shtml}}</ref>

<ref name=LAAMPS>{{cite web|url=http://lammps.sandia.gov/|title=LAMMPS Molecular Dynamics Simulator|publisher=]|access-date=October 29, 2012|first=Sergey|last=Zybin|archive-date=February 16, 2013|archive-url=https://web.archive.org/web/20130216080828/http://lammps.sandia.gov/}}</ref>

<ref name=anandsoftware>{{cite web|url=http://www.anandtech.com/show/6421/inside-the-titan-supercomputer-299k-amd-x86-cores-and-186k-nvidia-gpu-cores/3|title=Inside the Titan Supercomputer|page=3|publisher=Anandtech|first=Anand|last=Lal Shimpi|date=October 31, 2012|access-date=November 15, 2012|archive-date=April 5, 2013|url-status=live|archive-url=https://web.archive.org/web/20130405064443/http://www.anandtech.com/show/6421/inside-the-titan-supercomputer-299k-amd-x86-cores-and-186k-nvidia-gpu-cores/3}}</ref>

<ref name=messervid>{{cite web|last=Messer|first=Bronson|title=Using Titan to Model Supernovae|url=https://www.youtube.com/watch?v=-BY9K12TbUY|publisher=Anandtech|access-date=November 15, 2012|format=Youtube|date=October 30, 2012}}</ref>

<ref name=VERA>{{cite web|last=Pearce|first=Jim|title=VERA analyzes nuclear reactor designs in unprecedented detail|url=http://www.ornl.gov/info/ornlreview/v45_3_12/article05.shtml|publisher=Oak Ridge National Laboratory|access-date=December 18, 2012|archive-date=February 15, 2013|archive-url=https://web.archive.org/web/20130215105449/http://www.ornl.gov/info/ornlreview/v45_3_12/article05.shtml}}</ref>

<ref name=liveup>{{cite web|last=Munger|first=Frank|title=No. 1 Titan not yet living up to potential|url=http://www.knoxnews.com/news/2013/feb/20/no-1-titan-not-yet-living-up-to-potential/|access-date=March 26, 2013|publisher=Knox News|date=February 20, 2013|archive-url=https://web.archive.org/web/20130327070749/http://www.knoxnews.com/news/2013/feb/20/no-1-titan-not-yet-living-up-to-potential/|url-status=dead|archive-date=March 27, 2013}}</ref>

<ref name=solder>{{cite web|last=Huotari|first=John|title=Cray re-soldering Titan's connectors, supercomputer testing could be done in April|url=http://oakridgetoday.com/2013/03/13/titan-testing-could-be-done-by-may-cray-re-soldering-supercomputer-connectors|work=Oak Ridge Today|access-date=March 26, 2013|date=March 13, 2013|archive-date=March 18, 2013|url-status=live|archive-url=https://web.archive.org/web/20130318015011/http://oakridgetoday.com/2013/03/13/titan-testing-could-be-done-by-may-cray-re-soldering-supercomputer-connectors}}</ref>

<ref name=gpuson>{{cite web|last=Jones|first=Scott|title=Titan Users Now Have Access to GPUs|url=https://www.olcf.ornl.gov/2013/03/13/titan-users-now-have-access-to-gpus/|publisher=Oak Ridge Leadership Computing Facility|access-date=March 26, 2013|date=March 26, 2013|archive-url=https://web.archive.org/web/20130605073422/https://www.olcf.ornl.gov/2013/03/13/titan-users-now-have-access-to-gpus/|url-status=live|archive-date=June 5, 2013}}</ref>

<ref name=gtxtitan>{{cite web|last=Smith|first=Ryan|title=Nvidia's GeForce GTX Titan Review, Part 2: Titan's Performance Unveiled|url=http://www.anandtech.com/show/6774/nvidias-geforce-gtx-titan-part-2-titans-performance-unveiled|publisher=]|access-date=March 26, 2013|date=February 21, 2013|archive-url=https://web.archive.org/web/20130223083319/http://www.anandtech.com/show/6774/nvidias-geforce-gtx-titan-part-2-titans-performance-unveiled|archive-date=February 23, 2013}}</ref>

<ref name=cnnguns>{{cite web|last=Goldman|first=David|title=Top U.S. supercomputer guns for fastest in world|url=https://money.cnn.com/2012/10/29/technology/innovation/titan-supercomputer/index.html|publisher=]|access-date=March 31, 2013|archive-url=https://web.archive.org/web/20130302030515/http://money.cnn.com/2012/10/29/technology/innovation/titan-supercomputer/index.html|archive-date=March 2, 2013|date=October 29, 2012}}</ref>

<ref name=repairsdone>{{cite web|last=Huotari|first=John|title=Titan repairs complete, ORNL preparing for second round of supercomputer testing|date=April 8, 2013 |url=http://oakridgetoday.com/2013/04/08/titan-repairs-complete-ornl-preparing-for-second-round-of-supercomputer-testing/|publisher=Oak Ridge Today|access-date=April 8, 2013}}</ref>

<ref name=storage2>{{cite web|last=Santos|first=Alexis|title=Titan supercomputer to be loaded with 'world's fastest' storage system|date=April 16, 2013 |url=https://www.engadget.com/2013/04/16/titan-supercomputer-to-be-loaded-with-worlds-fastest-storage-system/|publisher=]|access-date=April 16, 2013}}</ref>

<ref name=accepted>{{cite web|last=Munger|first=Frank|title=Titan passes acceptance test, seals ORNL's supercomputer deal with Cray|url=http://blogs.knoxnews.com/munger/2013/06/titan-passes-acceptance-test-s.html|publisher=Knox News|access-date=July 2, 2013|archive-date=July 2, 2013|archive-url=https://archive.today/20130702192643/http://blogs.knoxnews.com/munger/2013/06/titan-passes-acceptance-test-s.html|url-status=dead}}</ref>

<ref name=tianhe>{{cite web|last=Munger|first=Frank|publisher=Knox News|title=Titan didn't re-test for TOP500, keeping last year's benchmark; ORNL's Jeff Nichols explains why|url=http://blogs.knoxnews.com/munger/2013/06/titan-didnt-re-test-for-top500.html|access-date=July 2, 2013|archive-date=July 30, 2014|archive-url=https://web.archive.org/web/20140730042157/http://blogs.knoxnews.com/munger/2013/06/titan-didnt-re-test-for-top500.html|url-status=dead}}</ref>

<ref name=tianhe2>{{cite web|title=June 2013|url=http://www.top500.org/lists/2013/06/|publisher=TOP500|access-date=July 2, 2013}}</ref>

<ref name=greenjune>{{cite web|title=The Green500 List - June 2013|url=http://www.green500.org/lists/green201306%26green500from%3D1%26green500to%3D100|publisher=Green500|access-date=July 2, 2013|archive-date=July 2, 2013|archive-url=https://archive.today/20130702194922/http://www.green500.org/lists/green201306&green500from=1&green500to=100|url-status=dead}}</ref>

<ref name=gemini>{{cite web|title=The Gemini Network|url=https://wiki.ci.uchicago.edu/pub/Beagle/SystemSpecs/Gemini_whitepaper.pdf|publisher=Cray Inc.|year=2010|access-date=29 April 2015|archive-date=January 28, 2015|archive-url=https://web.archive.org/web/20150128114004/https://wiki.ci.uchicago.edu/pub/Beagle/SystemSpecs/Gemini_whitepaper.pdf|url-status=dead}}</ref>

<ref name=bedorf>{{cite book|publisher=IEEE|year=2014|doi=10.1109/SC.2014.10|arxiv=1412.0659|bibcode=2014hpcn.conf...54B|isbn=978-1-4799-5500-8|last1=Bédorf|first1=Jeroen|last2=Gaburov|first2=Evghenii|last3=Fujii|first3=Michiko S.|last4=Nitadori|first4=Keigo|last5=Ishiyama|first5=Tomoaki|last6=Portegies Zwart|first6=Simon|title=SC14: International Conference for High Performance Computing, Networking, Storage and Analysis |chapter=24.77 Pflops on a Gravitational Tree-Code to Simulate the Milky Way Galaxy with 18600 GPUs |pages=54–65|s2cid=7008518 }}</ref>

}}


==External links== ==External links==
{{Spoken Misplaced Pages|Titan (Supercomputer) spoken.ogg|date=2016-7-8}}
*{{official website|http://www.olcf.ornl.gov/titan/}}
* {{commonscat-inline|Titan (supercomputer)}} * {{Commons category-inline|Titan (supercomputer)}}
* {{official website|http://www.olcf.ornl.gov/titan/}}
* {{cite web|title=GeForce GTX Titan|url=http://www.nvidia.com/titan-graphics-card|publisher=]|access-date=March 26, 2013|archive-url=https://web.archive.org/web/20130224082627/http://www.nvidia.com/titan-graphics-card|url-status=dead|archive-date=February 24, 2013}}


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Latest revision as of 01:57, 30 August 2024

American supercomputer This article is about the Titan supercomputer. For the Atlas 2 prototype computer, see Titan (1963 computer).

Titan
ActiveBecame operational October 29, 2012; decommissioned August 2, 2019
SponsorsUS DOE and NOAA (<10%)
OperatorsCray Inc.
LocationOak Ridge National Laboratory
Architecture18,688 AMD Opteron 6274 16-core CPUs
18,688 Nvidia Tesla K20X GPUs
Power8.2 MW
Operating systemCray Linux Environment
Space404 m (4352 ft)
Memory693.5 TiB (584 TiB CPU and 109.5 TiB GPU)
Storage40 PB, 1.4 TB/s IO Lustre filesystem
Speed17.59 petaFLOPS (LINPACK)
27 petaFLOPS theoretical peak
CostUS$97 million (equivalent to $129 million in 2023)
RankingTOP500: 4th, June 2017
PurposeScientific research
LegacyRanked 1 on TOP500 when built.
First GPU based supercomputer to perform over 10 petaFLOPS
Websitewww.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.

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.

History

Plans to create a supercomputer capable of 20 petaFLOPS at the Oak Ridge Leadership Computing Facility (OLCF) at Oak Ridge National Laboratory (ORNL) originated as far back as 2005, when Jaguar was built. Titan will itself be replaced by an approximately 200 petaFLOPS system in 2016 as part of ORNL's plan to operate an exascale (1000 petaFLOPS to 1 exaFLOPS) machine by 2020. The initial plan to build a new 15,000 square meter (160,000 ft) building for Titan, was discarded in favor of using Jaguar's existing infrastructure. The precise system architecture was not finalized until 2010, although a deal with Nvidia to supply the GPUs was signed in 2009. Titan was first announced at the private ACM/IEEE Supercomputing Conference (SC10) on November 16, 2010, and was publicly announced on October 11, 2011, as the first phase of the Titan upgrade began.

Jaguar had received various upgrades since its creation. It began with the Cray XT3 platform that yielded 25 teraFLOPS. By 2008, Jaguar had been expanded with more cabinets and upgraded to the XT4 platform, reaching 263 teraFLOPS. In 2009, it was upgraded to the XT5 platform, hitting 1.4 petaFLOPS. Its final upgrades brought Jaguar to 1.76 petaFLOPS.

Titan was funded primarily by the US Department of Energy through ORNL. Funding was sufficient to purchase the CPUs but not all of the GPUs so the National Oceanic and Atmospheric Administration agreed to fund the remaining nodes in return for computing time. ORNL scientific computing chief Jeff Nichols noted that Titan cost approximately $60 million upfront, of which the NOAA contribution was less than $10 million, but precise figures were covered by non-disclosure agreements. The full term of the contract with Cray included $97 million, excluding potential upgrades.

The yearlong conversion began October 9, 2011. Between October and December, 96 of Jaguar's 200 cabinets, each containing 24 XT5 blades (two 6-core CPUs per node, four nodes per blade), were upgraded to XK7 blade (one 16-core CPU per node, four nodes per blade) while the remainder of the machine remained in use. In December, computation was moved to the 96 XK7 cabinets while the remaining 104 cabinets were upgraded to XK7 blades. ORNL's external ESnet connection was upgraded from 10 Gbit/s to 100 Gbit/s and the system interconnect (the network over which CPUs communicate with each other) was updated. The Seastar design used in Jaguar was upgraded to the Gemini interconnect used in Titan which connects the nodes into a direct 3D torus interconnect network. Gemini uses wormhole flow control internally. The system memory was doubled to 584 TiB. 960 of the XK7 nodes (10 cabinets) were fitted with a Fermi based GPU as Kepler GPUs were not then available; these 960 nodes were referred to as TitanDev and used to test code. This first phase of the upgrade increased the peak performance of Jaguar to 3.3 petaFLOPS. Beginning on September 13, 2012, Nvidia K20X GPUs were fitted to all of Jaguar's XK7 compute blades, including the 960 TitanDev nodes. In October, the task was completed and the computer was finally renamed Titan.

In March 2013, Nvidia launched the GTX Titan, a consumer graphics card that uses the same GPU die as the K20X GPUs in Titan. Titan underwent acceptance testing in early 2013 but only completed 92% of the tests, short of the required 95%. The problem was discovered to be excess gold in the female edge connectors of the motherboards' PCIe slots causing cracks in the motherboards' solder. The cost of repair was borne by Cray and between 12 and 16 cabinets were repaired each week. Throughout the repairs users were given access to the available CPUs. On March 11, they gained access to 8,972 GPUs. ORNL announced on April 8 that the repairs were complete and acceptance test completion was announced on June 11, 2013.

Titan's hardware has a theoretical peak performance of 27 petaFLOPS with "perfect" software. On November 12, 2012, the TOP500 organization that ranks the world's supercomputers by LINPACK performance, ranked Titan first at 17.59 petaFLOPS, displacing IBM Sequoia. Titan also ranked third on the Green500, the same 500 supercomputers ranked in terms of energy efficiency. In the June 2013 TOP500 ranking, Titan fell to second place behind Tianhe-2 and to twenty-ninth on the Green500 list. Titan did not re-test for the June 2013 ranking, because it would still have ranked second, at 27 petaFLOPS.

Hardware

Titan uses Jaguar's 200 cabinets, covering 404 square meters (4,352 ft), with replaced internals and upgraded networking. Reusing Jaguar's power and cooling systems saved approximately $20 million. Power is provided to each cabinet at three-phase 480 V. This requires thinner cables than the US standard 208 V, saving $1 million in copper. At its peak, Titan draws 8.2 MW, 1.2 MW more than Jaguar, but runs almost ten times as fast in terms of floating point calculations. In the event of a power failure, carbon fiber flywheel power storage can keep the networking and storage infrastructure running for up to 16 seconds. After 2 seconds without power, diesel generators fire up, taking approximately 7 seconds to reach full power. They can provide power indefinitely. The generators are designed only to keep the networking and storage components powered so that a reboot is much quicker; the generators are not capable of powering the processing infrastructure.

Titan has 18,688 nodes (4 nodes per blade, 24 blades per cabinet), each containing a 16-core AMD Opteron 6274 CPU with 32 GB of DDR3 ECC memory and an Nvidia Tesla K20X GPU with 6 GB GDDR5 ECC memory. There are a total of 299,008 processor cores, and a total of 693.6 TiB of CPU and GPU RAM.

Initially, Titan used Jaguar's 10 PB of Lustre storage with a transfer speed of 240 GB/s, but in April 2013, the storage was upgraded to 40 PB with a transfer rate of 1.4 TB/s. GPUs were selected for their vastly higher parallel processing efficiency over CPUs. Although the GPUs have a slower clock speed than the CPUs, each GPU contains 2,688 CUDA cores at 732 MHz, resulting in a faster overall system. Consequently, the CPUs' cores are used to allocate tasks to the GPUs rather than directly processing the data as in conventional supercomputers.

Titan runs the Cray Linux Environment, a full version of Linux on the login nodes that users directly access, but a smaller, more efficient version on the compute nodes.

Titan's components are air-cooled by heat sinks, but the air is chilled before being pumped through the cabinets. Fan noise is so loud that hearing protection is required for people spending more than 15 minutes in the machine room. The system has a cooling capacity of 23.2 MW (6600 tons) and works by chilling water to 5.5 °C (42 °F), which in turn cools recirculated air.

Researchers also have access to EVEREST (Exploratory Visualization Environment for Research and Technology) to better understand the data that Titan outputs. EVEREST is a visualization room with a 10 by 3 meter (33 by 10 ft) screen and a smaller, secondary screen. The screens are 37 and 33 megapixels respectively with stereoscopic 3D capability.

Projects

In 2009, the Oak Ridge Leadership Computing Facility that manages Titan narrowed the fifty applications for first use of the supercomputer down to six "vanguard" codes chosen for the importance of the research and for their ability to fully utilize the system. The six vanguard projects to use Titan were:

  • S3D, a project that models the molecular physics of combustion, aims to improve the efficiency of diesel and biofuel engines. In 2009, using Jaguar, it produced the first fully resolved simulation of autoigniting hydrocarbon flames relevant to the efficiency of direct injection diesel engines.
  • WL-LSMS simulates the interactions between electrons and atoms in magnetic materials at temperatures other than absolute zero. An earlier version of the code was the first to perform at greater than one petaFLOPS on Jaguar.
  • Denovo simulates nuclear reactions with the aim of improving the efficiency and reducing the waste of nuclear reactors. The performance of Denovo on conventional CPU-based machines doubled after the tweaks for Titan and it performs 3.5 times faster on Titan than it did on Jaguar.
  • Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) is a molecular dynamics code that simulates particles across a range of scales, from quantum to relativistic, to improve materials science with potential applications in semiconductor, biomolecule and polymer development.
  • CAM-SE is a combination of two codes: Community Atmosphere Model, a global atmosphere model, and High Order Method Modeling Environment, a code that solves fluid and thermodynamic equations. CAM-SE will allow greater accuracy in climate simulations.
  • Non-Equilibrium Radiation Diffusion (NRDF) plots non-charged particles through supernovae with potential applications in laser fusion, fluid dynamics, medical imaging, nuclear reactors, energy storage and combustion. Its Chimera code uses hundreds of partial differential equations to track the energy, angle, angle of scatter and type of each neutrino modeled in a star going supernova, resulting in millions of individual equations. The code was named Chimera after the mythological creature because it has three "heads": the first simulates the hydrodynamics of stellar material, the second simulates radiation transport and the third simulates nuclear burning.
  • Bonsai is a gravitational tree code for n-body simulation. It has been used for the 2014 Gordon Bell prize nomination for simulating the Milky Way Galaxy on a star by star basis, with 200 billion stars. In this application the computer reached a sustained speed of 24.773 petaFlops.
  • VERA is a light-water reactor simulation written at the Consortium for Advanced Simulation of Light Water Reactors (CASL) on Jaguar. VERA allows engineers to monitor the performance and status of any part of a reactor core throughout the lifetime of the reactor to identify points of interest. Although not one of the first six projects, VERA was planned to run on Titan after optimization with assistance from CAAR and testing on TitanDev. Computer scientist Tom Evans found that the adaption to Titan's hybrid architecture was more difficult than to previous CPU-based supercomputers. He aimed to simulate an entire reactor fuel cycle, an eighteen to thirty-six month-long process, in one week on Titan.

In 2013 thirty-one programs were planned to run on Titan, typically four or five at any one time.

Code modifications

See also: GPGPU

The code of many projects has to be modified to suit the GPU processing of Titan, but each code is required to be executable on CPU-based systems so that projects do not become solely dependent on Titan. OLCF formed the Center for Accelerated Application Readiness (CAAR) to aid with the adaptation process. It holds developer workshops at Nvidia headquarters to educate users about the architecture, compilers and applications on Titan. CAAR has been working on compilers with Nvidia and code vendors to integrate directives for GPUs into their programming languages. Researchers can thus express parallelism in their code with their existing programming language, typically Fortran, C or C++, and the compiler can express it to the GPUs. Dr. Bronson Messer, a computational astrophysicist, said of the task: "an application using Titan to the utmost must also find a way to keep the GPU busy, remembering all the while that the GPU is fast, but less flexible than the CPU." Moab Cluster Suite is used to prioritize jobs to nodes to keep utilization high; it improved efficiency from 70% to approximately 95% in the tested software. Some projects found that the changes increased efficiency of their code on non-GPU machines; the performance of Denovo doubled on CPU-based machines.

The amount of code alteration required to run on the GPUs varies by project. According to Dr. Messer of NRDF, only a small percentage of his code runs on GPUs because the calculations are relatively simple but processed repeatedly and in parallel. NRDF is written in CUDA Fortran, a version of Fortran with CUDA extensions for the GPUs. Chimera's third "head" was the first to run on the GPUs as the nuclear burning could most easily be simulated by GPU architecture. Other aspects of the code were planned to be modified in time. On Jaguar, the project modeled 14 or 15 nuclear species but Messer anticipated simulating up to 200 species, allowing far greater precision when comparing the simulation to empirical observation.

See also

References

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Records
Preceded byIBM Sequoia
16.325 petaflops
World's most powerful supercomputer
November 2012 – June 2013
Succeeded byTianhe-2
33.9 petaflops
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