data center cooling - dps tele

Data Center CoolingA guide from:

1-800-693-0351 www.dpstele.com

“Your partners in UPS Monitoring Systems”


The air in your server room, especially nearest the processors in your equipment, will rise to dangerous temperatures quickly if not properly cooled and circulated. You don't want your servers and rack-mounted equipment taking in the hot air exhausted from other servers, otherwise you're likely to see equipment failures, or, at the very least, inefficient server activity. Even if you had enough air conditioning units that you could keep your server room at a reasonable temperature, you would expend a costly amount of energy doing so. There are far more efficient ways to keep your server room cool.

Air conditioning systems in the server room simply won't do a very good job of keeping your server room cool unless arranged in ways to maximize cooling potential. Air flow has to be controlled. There must be a way to ensure that the servers intake cold air, exhaust hot air, and that they don't exhaust their hot air into the intakes of other systems.

To deal with the problems involved in server room cooling, technicians are looking to the hot aisle strategy. In this strategy, servers and racks are placed in rows with their air intakes facing each other and exhaust facing away. This causes alternating hot and cold aisles. Cold air is pumped through holes in the raised floor in cold aisles. Servers take in the cold air, and exhaust it into hot aisles. In the hot aisles, CRAC (computer room air conditioner) units draw in the hot return air and cool it as it's pumped back below the raised floor, where it re-enters the system..

Some server rooms now even place ducts above the hot aisles, to help vent hot air. This utilizes the space above the servers toprovide another means by which hot air can escape the room. Of course, when allowing hot air to escape the room, technicians want to make sure that they keep that hot air in the system and utilize it to maintain a high, steady return air temperature. The hot air helps increase the efficiency of heat exchanger in CRAC units.

Because server room cooling relies on a number of different variables – air flow, humidity, return, and equipment distribution, you'll need to monitor the effectiveness of your server room's environmental systems in many places to ensure that the system is working properly. You can't simply leave environmental monitoring to the environmental controls in the server room, as they're placed only at areas where cooling, air flow, and humidity are most easily controlled.

Just because everything is fine with your CRAC units doesn't necessarily mean that the cold air is being distributed to the right spots in your server room. Humidity may be fine in your return-air space, but on the server room floor, at a different temperature, you may measure something different. The varied environment of the server room demands that you spread sensors and monitoring equipment throughout your server room.

To monitor various spots in the server room from a single device, DPS Telecom makes the TempDefender. The TempDefender is a small, rack mountable remote telemetry unit (RTU) that can handle up to 16 analog sensors reporting on all of the environmental factors in your server room. Sensors for the TempDefender may be daisy chained together, so you don't have to run a mess of cabling back to the TempDefender. You can also string sensors up to 600 feet away from the RTU, allowing you to run sensors to the most extreme spots in your server room from a centrally located device without worrying about connectivity issues.


TempDefender is capable of sending both SNMP traps and emails, so you can keep aware of developments in your server room without staring at a terminal. Reporting traps to a higher level master allows you to track trends in the server room and see where your server room's cooling systems are weakest. Trends also allow you to catch problems before they result in alarms. (A quickly rising temperature on an alarm, even prior to a threshold alarm, indicates a likely problem.) Emails sent from the TempDefender and NetGuardian remotes include a clickable link, so you can acknowledge the alarm from wherever you can get email, even your smartphone.

When setting sensors, you'll want to set and respond to minor thresholds just below or above optimum rates, so you can be aware of irregularities in your server room before they result in any harm or malfunction. Set temperature alarm thresholds at just above the air conditioning set-point for any particular area and major alarms within equipment-damaging levels. This will let you know when cooling equipment in the server room isn't functioning properly and gives you time to respond when servers approach critical temperatures.

Set airflow sensors near the intakes of your CRAC units in hot aisles and set the minor threshold for airflow just below the expected rates for intake. Humidity sensors should be set within acceptable levels for equipment but close enough to thresholds that you know that you're approaching unacceptable levels of humidity and can act to lower or raise it before your servers short.

Remember, despite being volatile, your server room needs to be kept under control. Smartly arranging racks and cooling equipment can help you keep it cool, but RTUs give you the actionable data to make sure it stays that way.


About Server Room Cooling

Air cooling requires air to circulateInefficient air circulation leads to higher energy costs/more frequent failures

Circulation process flow through serversCold air inHot air exhaustedCRAC (computer room air conditioner) takes in hot exhaust, outputs cold air


Server Room Cooling Strategy

• Hot Aisle Strategy• Racks line up facing each other in cold

aisles• Cold air pumped through floor tiles in • Servers exhaust hot air into hot aisles• CRAC Units intake hot air, pump cold

air back underneath floor


Hot/Cold Aisle Diagram


Dealing with Rising Hot Air

• Turn the space between the ceiling and the tops of servers into hot-air plenum

• Place ducts above servers• Intake hot air & use ventilation system

to push hot air to CRAC units


Monitoring Server Room Variables

HVAC services cannot effectively monitor server room environment

HVAC equipment monitors environment where it’s most controlledHVAC monitoring cannot monitor cold/hot air distribution & flow

Server Rooms have variable:Air FlowHumidityEquipment distribution (heat)


Monitoring Server Room Cooling

TempDefender can monitor up to 16 analog sensorsTemp, humidity, air direction/speedSensors can be daisy-chained & placed up to 600 feet away from TempDefender

Place sensors:Near expected hot spotsIn hot aisles to measure air flow to CRAC unitsAt both ends of cold aisles to ensure even cooling distribution & flowHumidity sensors in return air space


Central Monitoring Device: TempDefender


Monitoring Analog Thresholds

Set minor thresholds as alertsTemp: just above the set point for increased AC activityAir flow at just below expected speed

Minor alarms will alertyou to problems with environmental controlsbefore serious harmoccurs


Set SNMP Traps and Email Alerts

TempDefender can send SNMP Traps to your SNMP Master

Monitor the server room from your NOCTempDefender sends email notification of alarms

Monitor alarms from your laptop or smartphoneEmails contain a clickable link to acknowledge alarm


For Data Center Cooling & Monitoring Advice:

DPS Telecom• Monitoring reference site:

www.dpstele.com• Discuss your project:1-800-693-0351

data center cooling - dps tele

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