Presentation on theme: "Lecture 4: Power Provisioning Prof. Fred Chong 290N Green Computing."— Presentation transcript:
Lecture 4: Power Provisioning Prof. Fred Chong 290N Green Computing
Power Provisioning $10-22 per deployed IT Watt Given 10 year depreciation cycle – $1-2.20 per Watt per year Assume $0.07 per kilowatt-hr and PUE 2.0 – 8766 hours in a year – (8766 / 1000) * $0.07 * 2.0 = $1.22724 Up to 2X cost in provisioning – eg. 50% full datacenter = 2X provisioning cost
Underdeployment New facilities plan for growth Also discretization of capacity – Eg 2.5kW circuit may have four 520W servers 17% underutilized, but cant have one more
Modeling Costs TCO =datacenter depreciation + datacenter opex + server depreciation + server opex
$ per critical watt Cost / W Source $12-25Uptime Institute; the lower value is for Tier 1 designs that are rarely used in practice [ http://www.upsite.com/TUIpages/downloads/TUI808DollarsPer kW_WP.pdf ] http://www.upsite.com/TUIpages/downloads/TUI808DollarsPer kW_WP.pdf $10Microsofts purchase of two 10MW datacenters in for $200M; this cost excludes the value of land and buildings http://www.savvis.net/corp/News/Press+Releases/Archive/SAVVIS+Sells+Asset s+Related+to+Two+Data+Centers+for+200+Million.htm $10-16Dupont Fabros S-1 filing, discussing plans to build several 18MW datacenters http://www.secinfo.com/d14D5a.u5dFg.htm (page 6). A more recent article (http://www.reuters.com/article/pressRelease/idUS12552+06-Nov- 2008+PRN20081106?symbol=DFT.N), shows their facility having reached just over $10/W. http://www.secinfo.com/d14D5a.u5dFg.htmhttp://www.reuters.com/article/pressRelease/idUS12552+06-Nov- 2008+PRN20081106?symbol=DFT.N
Case A Dell 2950 III EnergySmart – 16GB of RAM and 4 disks – 300 Watts – $6K
Assumptions The cost of electricity is the 2006 average US industrial rate ay 6.2 cents/kWh. The interest rate a business must pay on their loans is 12%. The cost of datacenter construction is $15/W amortized over 12 years. Datacenter opex is $0.03/W/month. The datacenter has a PUE of 2.0. Server lifetime is 4 years, and server repair and maintenance is 5% of capex per year. The servers average power draw is 75% of peak power.
Case B higher-powered server – 500W – $2K energy cost of $0.10/kWh datacenter related costs rise to 46% of the total energy costs to 25% server costs falling to 31%. hosting cost of such a server, i.e., the cost of all infrastructure and power to house it, is more than twice the cost of purchasing and maintaining the server.
Utilization CPU Utilization of 50% => 75% Peak Power Nameplate 500W server – with all options (max mem, disk, PCI cards) – but more commonly 300W – Thus 60% utilized => 1.66x OPEX Vendor power calculator assumes 100% CPU utilization
Power Provisioning Problems Assume 30% CPU utilization and provision power accordingly – 200W instead of 300W – Variations could cause server to overhead or trip a breaker – Adding memory or disk would require physical decompaction of racks Thus 20-50% slack space common – Eg 10MW provisioned power => 4-6 MW actual power (plus PUE overhead)
Partial Utilization Costs Partially utilized servers use less power – Appear to cost less in OPEX cost per server – But produce less value in terms of applications Need metric for application value – Eg number of transactions, number of web searches – Divide TCO by metric – Eg TCO = $1M/month, 100M transactions/month => 1 cent / transaction – Eg TCO = $1M/month, 50M transactions/month => 2 cents / transaction (2X cost)