Impact of Virtualization on Data Center Physical Infrastructure White Paper #27. Tom Brey, IBM Operations Work Group

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1 Impact of Virtualization on Data Center Physical Infrastructure White Paper #27 Tom Brey, IBM perations Work Group 1

2 Virtualization Two Steps WP #19 USING VIRTUALIZATIN T IMPRVE DATA CENTER EFFICIENCY Data Center Data Center Data Center C L I N G Servers Storage Network P W E R C L I N G Servers Storage Network P W E R C L I N G Servers P Storage W E Network R 2 #27 Impact of Virtualization on Data Center Physical Infrastructure

3 Virtualization/Consolidation Talking Points Virtualization always increases efficiency Most always save energy on IT equipment But the rest of the DC may be running less efficient Virtualization requires high density data centers Remaining servers are running at higher power consumption levels But there are ways to deal with this Dealing with high density and high efficiency Less overall IT in a smaller space Get cooling closer to the load 3 I don t need to worry about power and cooling when virtualizing May need additional cooling in some areas Much less cooling in others

4 Physical Infrastructure Loss Characteristics Electrical Loss in kw (Waste due to inefficiency) PRPRTINAL loss N-LAD loss SQUARE-LAW loss Losses that occur at higher loads (ex. switching, conduction) Powered on without IT Load No Load 10% 30% 50% 70% 90% Full Load Equipment Loading 4

5 Very Simplified Example of the Role of Fixed Losses Electricity Savings vs. Efficiency Gains (Fans & Servers only) Pre-virtualization: 100 kw of servers Post-virtualization: 50 kw of servers Fan Fan motors 100kW motors Servers % kw 50% FIXED LSS Servers 100 kw 50% Total power consumption reduced by server reduction Servers Fan kw Fan motors 33% 100kW motors (no 100 change) kw 67% FIXED LSS 67% reduction in server power results in 56% electric bill savings 50% reduction in server power results in only 25% electrical bill savings In reality, much more to consider 5

6 Efficiency Curve PUE Right-Size Power-Cooling Equip 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% % IT Load Reducing IT Load Not considering redundancy 6

7 Which Density Strategy? New or existing data center? How many high density servers? How much bulk power and cooling? Can IT devices be moved around? Low-density racks with no virtualized servers Low-density racks with a mix of virtualized and non-virtualized servers High-density racks with virtualized servers Spread the load Supplemental Cooling Consolidate the load Spectrum of post-virtualization densities 7

8 Spread the Load Strategy Easy No new power and cooling equipment required But Takes up valuable floor space - lots of white space No power/cooling efficiency benefit New configuration could compromise existing cooling strategy/architecture Host servers inherit same availability as less critical servers CRAC CRAC Tape 91 F/ 33 C CRAC 8 Low Density Copyright Rack 2010, High The Green Density Grid Rack

9 Supplemental Cooling Strategy Inexpensive Low capital expense But Effective only for the lower range of high density Temporary solution for cooling of hot spots Supplemental Cooling Examples: Installation of fans to boost the cool air supply from the CRAC to an enclosure Variable speed drives (VFD) on CRAC units Better hot isle containment such as special racks (such as chimney-based racks) Installation of row-based air conditioners to address localized hot spots A rear-door heat exchanger shortens the air path to back of rack from CRAC 9

10 Consolidate to High and Low Density Areas Strategy Takes more planning Needs advance planning Perhaps retrofit only high density area CRAC CRAC rack row 91 F/ 33 C pod But has big advantages Predictable high-density cooling Enables higher-efficiency cooling Better utilization of floor space Enables targeted availability/redundancy 10 Low Density Rack High Density Rack Local cooling for hi-powered, dense equipment

11 When to Spread the Load Post-consolidation average kw/rack is less than 3 kw Placement of IT equipment is flexible IT equipment power and cooling redundancy requirements could limit mobility of IT equipment Additional power drops available only in certain locations Cooling redundancy may be based on physical location pen U-space is available in existing racks 11

12 When to Deploy Supplemental Cooling Post-consolidation average kw/rack is 3 kw 5 kw No flexibility over the placement of IT equipment Limited capital budget ptions: Specialty (grate-type) floor tiles or fans to boost the cool air supply Usage of portable spot air conditioning units Racks or rack mounted cooling devices which provides cooling directly at the rack Row-based air conditioners between two racks to address localized hot spots. 12

13 When to Designate High and Low Density Areas Post-consolidation average kw/rack is greater than 5 kw Subsection of data center is available for pod(s) Desire to improve overall data center efficiency (PUE) ptions: Improve hot air containment Reduce air path length * Top of Rack cooling * Row Cooling * Rear door heat exchanger Point: use high density area to focus on cooling efficiency 13

14 Characteristics of Dynamic Loads Row based cooling, CRAC VFD are methods to adjust to variable IT loads CRAC Room CRACs removed Row CRACs sense elevated temperature and increase fan speed to remove extra heat from hot aisle CRAC Hot spot When temperature decreases, row CRACs decrease fan speed to conserve energy CRAC Row CRACs added Hot spot CRAC CRAC CRAC Caution: Loads constantly shift as data center experiences higher/lower activity IT movement (VM Move) is typically unaware of cooling limits in any phy space 14

15 ther Considerations When Moving to High Density Typical complicate cable management Leftover cables when moving from low to high density Additional cables because of additional IT equipment Require higher rates of air flow to support heat load Increased weight of racks due to additional IT in rack Impact on power infrastructure (breakers, panels, etc.) 15

16 Summary Survey of Things To Consider during / after IT Virtualization The virtualization savings entitlement can be multiplied if power and cooling infrastructure is modified or upgraded Spreading the load, supplemental cooling, and designation of high density and low density areas can help further enhance data center efficiency performance No one size fits all Each approach to improve efficiency has pros/cons 16

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