Where Does the Power go in DCs & How to get it Back Foo Camp James Hamilton web: blog:

Agenda Power is the important measure – Power drives costs in that Data Center costs are 80% providing power and cooling infrastructure – Increasing concern about DC power consumption – Work done/watt Power In: Power Distribution & Optimizations Servers: Critical Load & Optimizations Heat Out: Mechanical Systems & Optimization 7/12/2008http://perspectives.mvdirona.com2

Power Distribution: Utility to CPU Power Conversions to server (each roughly 98%) – High (115kVAC) to medium(13.2kVAc) [differs by geo] – Uninterruptable Power Supply & Generators: Running at 13.2VAC UPS: can be rotary or battery – Good ones in 97% range. Much more common 93 to 94% – Common: rectify to DC, trickle to batteries, then invert to AC (~93%) – No loss at generators (please don’t start them: ~130gallons/hour * 10 or so) – 13.2kVACto 480VAC – 480VAC to 208VAC Conversions in Server to CPU & Memory: – Power Supply: 208VAC to 12VDC (80% common, ~95% affordable) – VRM: 12VDC to ~1.5VDC (80% common, 90% affordable) 7/12/2008http://perspectives.mvdirona.com3

Power Redundancy at Geo-Level Over 20% of entire DC costs is in power redundancy – Batteries able to supply up to 15 min at some facilities – N+2 generation (2.5MW) at over $2M each Instead, use more smaller, cheaper data centers Eliminate redundant power & bulk of shell costs Average UPS in the 93% range – Over 1MW wasted in 15MW facility 7/12/2008http://perspectives.mvdirona.com4

Power Distribution Optimization Rules to minimize power distribution losses: 1.Avoid conversions (Less transformer steps & efficient or no UPS) 2.Increase efficiency of conversions 3.High voltage as close to load as possible 4.Size voltage regulators (VRM/VRDs) to load & use efficient parts 5.DC distribution potentially a small win With regulatory issues Two interesting approaches: – 480VAC (or higher) to rack & 48VDC (or 12VDC) within – 480VAC to PDU and 277VAC to load 1 leg of 480VAC 3-phase distribution Common design: 44% lost in distribution – 1*.98*.98*.93*.98*.8*.8 => 56% (~4.4MW lost on 10MW total) – Affordable technology: 1*.99*.99*.95*.95 => 88% (~1.2MW total) 7/12/2008http://perspectives.mvdirona.com5

Critical Load Optimization Power proportionality is great but “off” is even better – Today: Idle server consumes ~60% power of full load – Industry secret: “good” data center server utilization around ~30% – Off requires changing workload location What limits 100% dynamic workload distribution? – Networking constraints VIPs can’t span L2 nets, ACLs are static, manual configuration, etc. – Data Locality Hard to efficiently move several TB & workload needs to be close to data – Workload management: Scheduling work over resources optimizing for power with SLA constraint Server power management – Most workloads don’t fully utilize all resources on server – Need ability to shut off or de-clock unused server resources – Very low power states recover more quickly Move from 30% utilization to 80% 7/12/2008http://perspectives.mvdirona.com6

CEMS: Thin Slice Computing Cooperating Expendable Micro-Slice Servers – Correct system balance problem with less-capable CPU Too many cores, running too fast for memory, bus, disk, … – Power consumption scales with cube of clock frequency Goal: ¼ the price & much less than ½ the power – Utilize high-volume client parts in server environment – Goal: 20 to 50W at under $500 – 1U form factor or less with service-free design Longer term goals – High-density, shared power supply & boot disk – Eliminate non-server required components – Establish viability of service free designs 7/12/20087http://msblogs/JamesRH

Conventional Mechanical Design Server fans (from components to air) CRACs: (from air to chilled water) – Air moving over long distance expensive – Air control often poor with hot/cold mixing Secondary water circuit (variable flow) Primary water circuit (fixed flow) – Water side economizer & A/C evaporator Condensate circuit – A/C condenser – Water side economizer – Cooling tower 7/12/2008http://perspectives.mvdirona.com8

Mechanical Optimization Simple rules to minimize cooling costs: 1.Raise data center temperatures 2.Tight control of airflow with short paths 3.Cooling towers rather than A/C 4.Air side economization (open the window) 5.Low grade, waste heat energy reclamation Best current designs have water close to load but don’t use direct water cooling – Lower heat densities could be 100% air cooled but density trends suggest this won’t happen Common mechanical designs: 24% lost in cooling Assume reduction to 1/3 current – 24% to 8% for 16% savings 7/12/2008http://perspectives.mvdirona.com9

Summary Some low-scale facilities incredibly bad Assuming current high-scale installation: – Power distribution savings ~32% Save 8% in power distribution to server Save further 24% power distribution losses in server – Cooling Savings: ~16% Conservatively estimate 1/3 the power using air-side economization 24% loss down to 8% for a 16% power savings – Server Utilization: ~90% Move from 30% to 80% through DC-wide workload scheduling 30% 60% of full load power to 80% 100% of full load power 2.6x work at 1.7x more power for a gain of 90% – Cooperative, Expendable, Micro-slice Servers: ~12% ½ the power but less capable server (most workloads are memory or disk I/O bound) Conservatively assume.8x work done.5x power => 30% savings 4.0x gains in work done/watt look attainable: – 1*1.32*1.16*1.90*1.30 => 3.8x (some overlap between CEMS & power dist savings) Power is #3 expense in DC behind server h/w, power distribution & cooling – Data center capital expense savings nearly 100% driven by power Reductions in power reduce capex, opex & is good for environment 7/12/200810http://perspectives.mvdirona.com

Slides These Slides: – werSavingsFooCamp08.ppt werSavingsFooCamp08.ppt Perspectives Blog: – 7/12/200811http://msblogs/JamesRH