data center floor design - your layout can save of kill your pue & cooling efficiency

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Data Center Floor Design – Your Layout Can Save or Kill Your PUE & Cooling EfficiencyThe following data center upgrade proposal demonstrates how floor layout has a major impact on data center performance. Implementing best practices and validating those practices through CFD models allowed Great Lakes to suggest a new layout that would provide an improved PUE, cooling costs reduction, and increased ROI.

Jason Hallenbeck, DCDC, explains the concepts behind how data center floor design can save or kill your PUE and cooling efficiency—as found in this proposal. Find Jason presenting at the BICSI Fall Conference on September 14th at 1:30pm.

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Executive SummaryGreat Lakes began a recent dialogue with a customer regarding current operations and the potential for performance improvement within the customer data center.

After a series of initial conversations, the customer expressed a desire to gain an assessment of the current operational status of the company’s data center, along with data center infrastructure management (DCIM) recommendations which could provide multi-generational support as the company’s IT needs continue to evolve.

Great Lakes Case & Cabinet was contracted to provide a comprehensive evaluation of the customer’s Data Center and to conduct complete computational fluid dynamics (CFD) analysis of the facility in its current form. Numerous site visits were conducted and numerous on-site measurements were taken. The operational capabilities of the current data center were captured in a CFD to establish baseline standards against which any potential future improvements might be measured.

Great Lakes was also asked to look at the short, medium and long term potential for increased density within the data center as well as an expansion of IT operations within the space. As part of that effort, Great Lakes would offer infrastructure recommendations, supported by CFD analysis which would create real world performance estimates of future operations within the data center, as those recommendations might be implemented.

The following pages outline the scope of work performed by Great Lakes as well as the presentation of data collected, infrastructure recommendations made to the management of the data center (along with estimates and ROI for recommended solutions) as well as CFD modeling designed to estimate data center performance conditions as those recommendations might be implemented.


Overview Phase 1Recommended Action Plan:The following recommendations are described to increase the performance and efficiency of the data center based on the modeling data and discussions with the data center team.

Phase 1 includes:• Network Core tile migration pg. 4-7• Removing under-floor baffle pg. 8-9• Migrating Floor Tiles pg. 10-11• Cold aisle and enclosure containment pg. 12-19• Eliminate air re-circulation in current enclosures

Deployment of cold aisle containment Core switch migration pg. 20-25

• Increasing CRAC unit set point (as desired) pg. 26-27

Additional Information:• Recommended action plan pg. 28• PUE, Cooling Cost Reduction and ROI pg. 29• Conclusion pg. 30


Network Core (Baseline)

Enclosure 207

Rendered view Rendered view with airflow patterns

Rendered view with airflow patterns

Enclosure 207 was chosen for an internal view to demonstrate the airflow patterns inside the enclosure. The excess air introduced by the unsealed cable cut-out lowers the temperatures inside the enclosures in the row protecting the side-to-side airflow equipment from overheating.


Network Core (Baseline)


Network Core (Phase 1)

Enclosure 207

Rendered view Rendered view with airflow patterns

Rendered view with airflow patternsEnclosure 207 was chosen for an internal view to demonstrate the airflow patterns inside the enclosure. The excess air introduced by the unsealed cable cut-out lowers the temperatures inside the enclosures in the row protecting the side-to-side airflow equipment from overheating.

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Perforated floor tiles have been moved to provide a higher flow of conditioned air to the equipment. A high flow tile was place


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Network Core (Baseline)• Side to side airflow equipment creating a

cascading heat elevation scenarioUnblocked cable cutouts provide a supply of cool air inside the enclosure

This reduces the temperature cascading effect

Network Core (Rearranged floor tiles)• Floor tiles reorganized providing higher flow

of air directly in front of the enclosures• High flow tile installed in front of #207 to

provide additional airflow to core switches in nearby enclosures

• Sampling the temperatures at enclosure #204 we can see a 7.1o Fahrenheit decline in temperature.

Temp at 81.5o F

Temp at 74.4o F


Under-floor (Baseline)

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Entrance

With the under-floor plenum installed, the secondary zone created is highly pressurized. In addition, there is minimal to no load in the secondary zone. This greatly reduces the efficiency of the two CRAC units installed in the zone. It is recommended that this barrier be removed to allow the two units to supply additional cooling to the entire room.


Under-floor (Phase 1)

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With the plenum barrier removed, the CRAC units airflow from the secondary zone can travel to the entire data center supporting IT loads where needed. This is especially significant when utilizing cold aisle containment. With the cold aisle contained the proximity of the CRAC unit in a data center to the load becomes less critical. Every unit in the data center can supply conditioned air to the entire facility. In the event of unit(s) failures(s) provided that the overall cooling capacity does not fall below the IT load the equipment will continue to operate without interruption. This increases uptime by reducing the criticality of any one unit, and makes unit maintenance more manageable.

Entrance


Tile Migration

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Tile migration for phase 1 development. By removing tiles in the hot aisle and locations not directly near IT equipment the under-floor pressure increases creating a higher velocity of airflow to the equipment providing better cooling. In addition, by reducing the amount of conditioned air mixing with exhaust air the return temperature to the CRAC units increases which increases the efficiency of the entire HVAC system.

Entrance


Equipment Orientation - Baseline

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Shown is the current layout of enclosures and floor tiles in the data center. The red X on the CRAC unit indicates that it is currently non-operational.

Entrance


Aisle Completion with Enclosures

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The following enclosures are recommended to complete the rows. These were based on discussions with IT and their future expansion plans.

GL840ES-2442 enclosures - qty 13 (2 enclosures will replace enclosures highlighted in red)· #1— Qty. 2· #2— Qty. 6· #3— Qty. 5GL840ENT-3242MSS enclosures—qty 3 · #4— Qty. 3

1

2

3

4


Equipment Orientation – Phase 1

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Phase 1 layout shows the completed rows, migrated tiles overhead panels and aisle doors are hidden to show cold aisles.

Entrance


Server Farm (Baseline)• Unfinished rows increase potential for

recirculation of hot air• Open rack spaces create short circuits inside the

enclosure, allowing conditioned air to bypass equipment and hot aisle to recirculate back into the equipment intakes

Server Farm (Phase 1)• Additional enclosures complete rows and segregate

hot and conditioned air• Open rack spaces have filler panels installed to

reduce short circuits• Cisco 6500 switches migrated from EMC

enclosure to 30” wide enclosure • Floor tiles have been moved from other areas in the

datacenter to complete cold aisle • Model temperature comparison shows a 10.9o F

71.9oF

61.1oF


Server Farm Cold Aisle Containment

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Shown is an overhead view of the complete aisles with containment doors at the end of the aisles and overhead containment panels containing conditioned air in the cold aisle. This design was tested based on discussion with the data center team based on its ability to reduce the criticality of any one CRAC unit failure, eliminates hot air re-circulation improving the performance and extending the life of the equipment.



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Great Lakes enclosures were added to rows of enclosures already installed in the server farm area of the data center. The completed rows allow better hot and cold air segregation. Completed rows would also allow the installation of aisle containment doors.

Enclosures already installed in the data center

Great Lakes enclosures



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Each aisle in the server farm was contained using a single, custom aisle door (model shows two doors which represents standards aisle doors offered by Great Lakes).



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In addition to single aisle doors, Polargy Polarplex panels were installed across the top of the rows to trap cool air in. Floor tiles from other locations in the data center were moved to the aisles to create a row of fully perforated floor tiles (a mixture of standard and high flow tiles).

Single, custom aisle door

PolargyPolarPlexPanels

Perforated floor tile

High flowfloor tile



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Because there was a height difference between the existing enclosures and the new Great Lakes enclosures, a custom support bar was designed to create a level service to properly mount the Polargy PolarPlex Panels to.

Height difference between the existing enclosures (left) and Great Lakes enclosures (right).

Custom support bar


San Switch Migration: Phase 1

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Cisco Catalyst 6509-E core switches are migrated to two of the GL840ES-3048 enclosures in the 700 row. Baffle kits are installed to prevent air recirculation from one switch to the next eliminating the potential for cascading heat issues.


San Switch: Phase 1(Phase one)

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Baffles reduce recirculation by directing conditioned air toward the intake side and exhausting the hot air toward the cold aisle. Used in conjunction with a brush grommet kit, side-to-side airflow operates efficiently in a hot aisle/cold aisle configuration.

Intake side(baffle side hidden) Exhaust side


Baseline: Top View

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1. Highest temp in the cold aisle currently. Model data average temp 73.6F

2. Network core temps outside of the enclosure reach upwards of 75F

Entrance

CRAC Unit Specifications

Set Point 72° F

Supply Temp. 61° F


Phase 1: Top ViewPolargy panels hidden to make cold aisle visible

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1. Cold aisle temp consistent at 62.2°F2. Network core temps outside of the enclosure at 73.4°F3. Migrated SAN switches are active and exhausting temps at 82°F

By implementing containment, cold aisle temperatures are within a few degrees of under-floor tile supply. This allows the CRAC units to be increased in one degree increments and cold aisle temps will increase accordingly.

CRAC Unit Specifications

Set Point 72° F

Supply Temp. 61° F

Entrance


Baseline: Look Down View

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Phase 1: Look Down View

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SAN switch migration creating temps of 87°F


CRAC Unit Failure Analysis: Baseline

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90.1°F Temp

When the CRAC unit with the highest load on it (conditioning the most air in the data center) is shutdown, the hot air from the server farm (specifically the blade server enclosures) travels to the next nearest unit. This increases the load on that unit as well as increases the cold aisle temperatures. This scenario creates massive short cycling of hot air, increasing the equipment intake temperatures, resulting in equipment “thermal-ing down/off” or failing.


CRAC Unit Failure Analysis: Phase 1

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When cold aisle containment is implemented and the CRAC unit is shut down the hot air continues to travel to the nearest available unit. However, with the cold aisle contained a consistent flow of conditioned air is supplied into the aisle equipment intakes; no hot air short cycling can occur, resulting in uninterrupted service in the event of a single unit failure. Temps taken at enclosure 508 show a delta of 8 degrees Farenheit. In addition temps taken in the cold remain a consistent 60-63 degrees F.

82.1°F Temp


Recommended Action Plan

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Recommended Action Plan• Network Core tile migration pg. 4-6• Migrating floor tiles pg. 9• Removing under-floor baffle pg. 7-8• Cold aisle and enclosure containment pg. 10-14

o Completing aisles with enclosures pg. 11-13o Eliminate air re-circulation in current

enclosureso Install filler panels in open RMUo Install solid top panels— IT3 Install

side panel blanks— IT4• Deployment of cold aisle containment

o Install Polargy Polar-Plex panels-IT6o Install aisle containment doors- IT1/IT2

• Core switch migration pg. 15-16o Installation of Baffle Kits— ESSAB14

• Increasing CRAC unit set point (as desired) -For every degree the set point is raised 4% efficiency gain*

*Source: The American Society of Heating Refrigeration and Air Conditioning Engineers TC 9.9


PUE, Cooling Cost Reduction and ROI

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PUE (Power Usage Effectiveness):

Average PUE for 2011 (based on data provided) 1.84

PUE estimate (after phase 1 completion) 1.39

Current and Projected cooling costs:

Current average monthly cooling cost (based on data provided) $4,153.38

Projected average monthly cooling cost $1,930.75

Estimated savings $2,222.63*

*Projected average savings and ROI can be improved by raising set point(s), reducing fan speed and cycling CRAC units. Performance will vary based on system flexibility and tolerances


ConclusionGreat Lakes has designed and modeled a solution that provides the customer with a data center upgrade plandesigned to increase the energy efficiency and reliability of their current design by segregating hot and cold air optimizing air delivery, and deploying cold aisle containment.

Recommendations:1. Adjust the floor tiles providing airflow to the enclosures at the network core. Moving the tiles directly in front of

the enclosures will allow a greater supply of conditioned air to reach the equipment, greatly improving the exhaust temperature of the airflow equipment installed in the racks and lowering the internal enclosure temperatures. This effort will result in a decreased risk of thermal issues: performance degradation, thermal shutdown, and early equipment mortality.

2. Create and fully contain the cold aisles in the server farm. This can be achieved in several steps: redeploying and consolidating floor tiles; completing the aisles with enclosures; installing filler panels in any unused RMU; and containing the cold aisle through the use of end of row doors and overhead containment panels.

Through containment, the conditioned air is segregated from hot exhaust air. Contained conditioned air will remain at delivered temperature until used by the equipment. Another advantage of cold aisle containment is consistency in cold aisle temperatures which will be very close to the supply temperatures of the CRAC units. Any increase to the set points of the CRAC unit should proportionally increase the conditioned air supplied to the cold aisle. This should make it much easier to the deliver a consistent supply temperature to every piece of equipment.

Modeling revealed that the removal of the under floor baffle could increase the amount of cooling capacity to the entire room. A fully open raised floor, in conjunction with cold aisle containment, could reduce the impact a single CRAC unit failure will have on the data center. This scenario was modeled at the CRAC unit with the highest load in the server farm. Hot aisle temperatures increased dramatically, while the cold aisle remained at supply temperatures.


ConclusionBy completing the Phase 1 recommendations, the data centers overall performance will be improved by:

Better utilizing the conditioned air• Balancing the load per CRAC unit more effectively• Increasing the available capacity (in RMU) on the datacenter floor space• Significantly reducing recirculation in the enclosure

Improving reliability• Reduced intake temperatures increasing equipment lifespan• Balanced CRAC unit load reduces dependency on a single unit failure• Cold aisle containment allows the server equipment to continue operation even when closest

proximity CRAC unit fails

data center floor design - your layout can save of kill your pue & cooling efficiency

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