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Lecture 4: Power Provisioning Prof. Fred Chong 290N Green Computing.

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Presentation on theme: "Lecture 4: Power Provisioning Prof. Fred Chong 290N Green Computing."— Presentation transcript:

1 Lecture 4: Power Provisioning Prof. Fred Chong 290N Green Computing

2 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

3 Power Distribution Revisited

4 Measured Load vs Power

5 Modeled vs. Measured PDU Power

6 Methodology

7 Workloads Websearch – high request throughput and large data size Webmail – high I/O Mapreduce – large offline batch jobs

8 Websearch Results

9 Webmail Results

10 Mapreduce Results

11 Mixed Load

12 Real Datacenter

13 Time at Power Level 80 servers 800 servers 8000 servers

14 Oversubscription Opportunity 7% for racks (80) 22% for PDUs (800) 28% for clusters (8000) – Could have hosted almost 40% more machines

15 Power Capping

16 Observed Power


18 Idle Power

19 Energy Savings

20 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

21 Modeling Costs TCO =datacenter depreciation + datacenter opex + server depreciation + server opex

22 $ per critical watt Cost / W Source $12-25Uptime Institute; the lower value is for Tier 1 designs that are rarely used in practice [ kW_WP.pdf ] kW_WP.pdf $10Microsofts purchase of two 10MW datacenters in for $200M; this cost excludes the value of land and buildings s+Related+to+Two+Data+Centers+for+200+Million.htm $10-16Dupont Fabros S-1 filing, discussing plans to build several 18MW datacenters (page 6). A more recent article ( 2008+PRN20081106?symbol=DFT.N), shows their facility having reached just over $10/W. 2008+PRN20081106?symbol=DFT.N

23 Case A Dell 2950 III EnergySmart – 16GB of RAM and 4 disks – 300 Watts – $6K

24 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.

25 Cost Breakdown A

26 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.

27 Cost Breakdown B

28 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

29 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)

30 Case B with 50% Occupancy

31 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)

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