Configuring cooling

Understanding real-time temperature predictions The approach to predicting data center cooling performance in real time pioneered by Schneider Electric is to focus on airflow patterns rather than temperature predictions. Airflow patterns, after all, are the root cause of cooling success or failure whereas temperatures are merely a symptom. It is possible to have acceptable temperatures while the management of cooling airflow is out of control and inefficient. Additionally, while airflow patterns are dominated by characteristics of nearby racks and coolers, temperatures "float" up or down with the surrounding ambient temperature. Consequently, it is easier to develop real-time cooling-prediction algorithms which predict airflow pattern characteristics rather than predicting temperatures directly. The primary metric developed for airflow-pattern prediction is the Capture Index (CI) which is defined as either the fraction of a rack's airflow which comes directly from local cooling sources (Cold Aisle CI) or the fraction of the rack's airflow which is captured by local sources (Hot Aisle CI). Once airflow patterns are known, however, it is possible to estimate all of the temperatures of primary interest (rack and cooler inlet and outlet temperatures and a room ambient temperature).

Tips and tricks for configuring cooling Here is a collection of tips and tricks for configuring cooling in the application. If you have any tips of your own that could be useful to others, feel free to share them by adding a comment to the bottom of the page. Adjusting estimated power load and cooling airflow You can improve the accuracy of the cooling estimates to fit your particular setup by providing the system with as much information about the power and cooling in your data center as possible. More... Viewing CI values in the Cooling view If you do not see CI values as expected for some equipment in the Cooling view, see Troubleshooting why Capture Index values do not display. Customizing colors and temperature thresholds In the 3D view, you can click the icon at the bottom of the thermometer to customize the temperature range. You can adjust the thresholds for maximum and minimum temperature and customize the colors of the temperature scale. If the thermometer does not show, click the arrow icon to invoke it. To customize the graphical representation of the velocity arrows, use the settings in Tools>Preferences. These settings define how the arrows will indicate the velocity in the Floor Layout Floor Plenum view and in the 3D Velocity plane. The different velocities will be represented as arrows of a certain length or color. Dragging InRow OA cooling units into the layout If you cannot drag an InRow OA cooling unit into the layout, you may be trying to drag it into an unsupported position. InRow OA cooling units are positioned over a hot aisle between two rows of racks to move the source of cooling close to the heat load in a thermal containment system. Drag a Hot Aisle Containment system into the layout before dragging an InRow OA cooling unit between the rows. Duct-to-ceiling When using the duct-to-ceiling feature please make sure that you balance the airflow. The amount of airflow coming from the ducted racks should be similar to the amount of airflow to the ducted cooling units. If there is a large unbalance the air will leak in or out from the ceiling. This is handled by the cooling calculator, but the results can be difficult to interpret. One indication that the calculations encounter an under-pressure in the ducted ceiling is that the Cooling Load on the cooling units is very low.

Row-based or room-based cooling Row-based cooling Cooling is distributed through InRow® cooling units placed in the rows close to the heat generating equipment. 102239146_360037995394.png Room-based cooling Cooling airflow is distributed through perforated tiles in a raised floor environment. Cooling calculations include airflow distributed via perforated tiles for equipment spanning cold aisles with perforated tiles positioned in the cold aisle. 102239140_360037995394.png

Optimizing the cooling configuration accuracy by adjusting power and cooling estimates Since IT Advisor uses estimates to calculate the temperatures in the 3D view, you cannot expect the simulation to be completely accurate. However, you can improve the accuracy of these estimates to fit your particular setup by providing the system with as much information about the power and cooling in your data center as possible. Server load estimates In IT Advisor, every server in the data center has two power estimates. By default, the two values are the same. They define the maximum power consumption for a particular server in its maximum configuration. Manufacturer's Nameplate: Identifies the nameplate value of the selected server. IT Advisor uses this value as the reference value. Estimated Load: Identifies the estimated load of the selected server. IT Advisor uses this value for the calculations. You can lower the Estimated Load for all servers in the data center if they do not consume all the power specified by the nameplate value. The option is available if you right-click the server and select Properties>Power. Cooling unit airflow estimates The accuracy of the cooling unit airflow is about 85-90% in typical configurations. However, you can adjust the airflow properties for the cooling units if the default values in the system do not match your specific setup. The option is available if you right-click the cooling unit and select Properties>Cooling. In this way, you can provide the system with the specific power and cooling values for your data center and improve the accuracy of the configuration.

Exporting cooling data to 3rd party applications If you want to export cooling data from IT Advisor and use it in other applications, you can use the export options. In File>Export, select the type of data to export and export it to your local or network drive. 102239155_360038495793.png Export types and formats Temperature map in Comma Separated Values file format Plenum airflows in Comma Separated Values file format Computational Fluid Dynamics model in (APC by Schneider Electric, open) xml file format Computational Fluid Dynamics model in (FloVENT) PDML file format

Designs with CRAC Units Placed Outside the Room Starting from version 7.4 IT Advisor allows modeling of ceiling tiles, downflow CRAC units with air duct to ceiling plenum and cooling units placed outside a room. Add CRAC units by dragging them from the Genomes pane into the layout. Place them outside the room, but touching room walls. Enable Duct to ceiling by right-clicking the item, and selecting Properties, and using the settings in the Cooling page. Configure room to use Drop ceiling. Drag ceiling tiles from the Genomes pane into the layout. Add at least one ceiling tile for each CRAC unit. Place these tiles touching the same wall as CRAC unit. 102239152_360037994794.png

Cooling redundancy In IT Advisor, cooling redundancy refers to the amount of redundant cooling units in this way: N: There are no redundant cooling units for the rack. There are one or more coolers in the data center. If ONE cooler fails anywhere in the data center, it would result in inadequate cooling (yellow or red CI). N+1: There is one redundant cooling unit for the rack. ONE cooler (CRAC, row-based, or OA unit) can fail anywhere in the data center and cooling will still be adequate (green CI). N+2: There are two redundant cooling units for the rack. TWO coolers (CRACs, row-based, or OA units) can fail anywhere in the data center and cooling will still be adequate (green CI). N+x: There are x redundant cooling units for the rack. X coolers (CRACs, row-based, or OA units) can fail anywhere in the data center and cooling will still be adequate (green CI).

Cooling configuration accuracy The Potential Flow Models (PFM) used in this application are typically within about 10% of CFD for Capture Index, Average Rack Inlet Temperature, and perforated tile airflow; they are not as good at predicting maximum rack inlet temperatures. Cooling design guidelines For the most efficient cooling design, equipment should be placed in clusters. An equipment cluster is two nearly-equal-length rows of equipment separated by a hot or cold aisle. A row of equipment can be a member of one or two clusters. All heat generating equipment (racks and UPS) properly positioned in rows will show up color-coded in the Floor layout. However, you will experience better cooling performance with well formed clusters: All rows are of similar length and aligned across hot or cold aisles. The equipment rows do not include blocks, gaps, or spaces. In Hot Aisle Containment Systems (HACS), cooling units are positioned in pairs directly across from each other. Example: Well formed cluster 102237742_360037994714.png Cooling performance predictions, which assume the racks are populated evenly, will be more accurate if racks are populated in bottom-to-top order and for more regular room shapes and well-formed hot/cold aisle layouts. Note If you flip a row to face front to back, it affects the cooling simulation for up to 3 rows. Cooler airflow specifications Cooler airflow in cubic feet per minute (CFM) is assumed to be: Cooler type Minimum CFM Maximum CFM InRow RC (300 mm) 1450 2900 InRow RC (600 mm) 2760 6900 InRow RP (600 mm Chilled Water) 2760 6900 InRow RP (600 mm Air Cooled) 1920 4800 InRow RD (600 mm Air Cooled) 2000 5000 InRow RD (300 mm Air Cooled) 916 2300 InRow RD (300 mm Fluid Cooled) 916 2300 Rack airflow is by default assumed to be 160 CFM/kW based on the total rack power. This value can be changed by right-clicking a rack and selecting Properties, to change to, for example, 105 CFM/kW for blade server racks. CRAC airflow is, by default, assumed to be 6000 CFM. This can be changed by right-clicking a CRAC and selecting Properties. UPS airflow is automatically calculated by the system based on the UPS size and the number of power modules (assumed to be 10kW each). Airflow through each tile is calculated as the tiles are positioned in the layout. Airflow for generic powered equipment is not included in the cooling calculations by default. This can be changed by right-clicking a piece of generic powered equipment and selecting Properties.

The graphical floor plan of the configured data center layout includes overlays showing capture index (CI), plenum pressure, plenum velocities, and 3D rendering of the temperature map, including airflow, temperature thresholds, load. These overlays give you a fail/pass indication of the effectiveness of the active cooling configuration. As the design takes place, you get a qualified estimation of the effect of changes in supply temperature, airflow, and number of cooling units and room-based cooling parameters. Capture index The Cooling overlay of the data center floor layout shows a color-coded overview of the Capture Index. You can use this view to get an overview of the reasons why the tile airflow may not be the same across the room. Each rack in a well-formed hot aisle / cold aisle layout shows a color-coded capture index percentage. The CI value identifies inlet air which is supplied by what fraction of the equipment's exhaust airflow is captured by the InRow® cooling units included in that row pair or by the CRAC or CRACs in the room through the perforated tiles. 102237742_360037994714.png Plenum velocities Subsequently, you can use the Floor Plenum overlay to drill down into looking at specific velocity issues in the plenum and estimate perforated tile airflow rates. When you drag in a new cooling unit or move a perforated tile, the flow vectors and perforated tile flow rates update instantly. 102237276_360038495373.png Plenum pressure For data center layouts with raised floor environments, you can use the Floor Plenum Pressure overlay to drill down into looking at specific pressure issues in the plenum. 102237745_360037995794.png 3D temperature map In the 3D view, you can see the room's airflow above the raised floor. Velocity vector and temperature results look like those from traditional CFD applications and provide the same ability to quickly locate problem spots and understand the underlying causes. You can have multiple rooms open in the 3D view at a time. When you have opened a room in 3D view or applied changes to the configuration, click Calculate to show the updated view. Subsequently, you can select File > Export and export to .xml or export directly to .pdml without using conversion tools. 102237275_360038495373.png