Data center & server room monitoring recommended standards & best practices


On this page you will find the standards recommended by ASHRAE for monitoring the environment in your data center or server room. The settings below apply to A1-A4 class data centers and server rooms. Environmental standards are provided for rack level monitoring, ambient monitoring and water leak detection.


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1. Rack Level Monitoring


Summary: ASHRAE recommends no less than 6 temperature sensors per rack. However Gartner says that 3 could already be enough. Intake temperature should be between 18-27C / 64-80F. Outtake temperature should be less than 20C / 35F compared to the intake temperature.

Background Info: Based on a recent Gartner study, the annual cost of a Wintel rack averages around $70,000 USD per year. This excludes the business cost of a rack. Risking losing business continuity or even your infrastructure due to environmental issues is not an option. But what are the environmental threats at a rack level?

A mistake often made is to only rely on monitoring the conditions at a room level and not at a rack level. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends no less than 6 temperature sensors per rack in order to safeguard the equipment. They should be mounted at the top, middle & bottom and this both at the front & back of rack.

When a heat issue arises, air conditioning units will initially try to compensate the problem. When you are doing temperature monitoring at a room level only, then the issue will only be detected when the air conditioning units are no longer capable of compensating the heat problem. It may be too late then... Rack temperature is also not server temperature.

As Gartner stated, you could already start at monitoring rack temperature with 3 measurement points: at the bottom front of the rack to verify the temperature of the cold air arriving to the rack (combined with airflow monitoring); at the top front of the rack to verify if all cold air gets to the top of the rack; and finally one at the top back of the rack which is typically the hottest point of the rack. Intake temperature should be between 18-27C / 64-80F. Outtake temperature should be less than 20C / 35F compared to intake temperature.

What is the impact of temperature on your systems? High end systems have auto shutdown capabilities to safeguard themselves against failures when temperature is too high. But did you know that CPU level errors and as such errors in your applications can be temperature induced? On top of that heat will stress fan equipment even more. This reduces equipment life time expectance. All this affects your system's availability and your business continuity.

For small rooms it is recommended to go with wired sensors. In larger data centers where you need a lot of monitoring points, wireless sensors can offer a cheaper alternative. With wireless sensors there is no cabling required. You'll also need substantially less IP addresses as 30 temperature sensors can talk to 1 base unit. non-relevant transparent gif

2. Ambient room monitoring


Summary: Room monitoring, the temperature has to be maintained between should be between 18-27C / 64-80F. Humidity range is 40% and 60% rH. Dew point temperature should be 5.5C DP to 60% RH and 15C DP.

Background Info: Ambient server room monitoring or data center monitoring is the environmental monitoring of the room for its humidity and temperature levels. Temperature and humidity sensors are typically deployed in:
  • potential hot zones inside the server room or data center
  • near air conditioning units to detect failure of such systems.

    When multiple air conditioning systems are available in a room, then a failure of one system will initially be compensated by the others before it may lead to a total failure of the cooling system due to overload. As a result temperature / airflow sensors are recommended near each unit to get early failure detection.

    Monitoring humidity is equally important than temperature and often omitted. Did you know that the relative humidity (rH) in server rooms and data centers should be between 40% and 60% rH. Too dry will result in the build up of static electricity on the systems. Too humid and corrosion will start slowly damaging your equipment resulting in permanent equipment failures.

    When using cold corridors inside the data center, then the ambient air temperature outside the corridor may be at higher levels. Air temperature of 37C / 99F are not uncommon in such setups. This allows to significantly reduce the energy cost. However this also means that temperature monitoring is of utmost importance as a failing air conditioning unit will have a way faster impact on the systems lifetime and availability (fans stress, CPU overheating, ) and running a room at higher temperatures may also affect non rack mounted equipment.

    When using hot corridors it is important to monitor temperature across the room to ensure that sufficient cold air gets to each rack. In this case however one can also rely on rack based temperature sensors in addition of temperature and humidity sensors close to each air conditioning unit. non-relevant transparent gif

    3. Water & Flooding Monitoring


    Summary: Water leak sensors should be put around the perimeter of the room, under each AC unit and under each pipe running through the server room or data center.

    Background Info: Water leakage is a less known threat for server rooms & data centers. The fact that most data centers and server rooms have raised floors makes the risk even bigger as water seeks the lowest point.

    Two type of sensors for water leakage can be commonly found: spot and water snake cable based. Spot sensors will trigger an alert when water touches the unit. Water rope or water snake cable sensors use a conductive cable whereby contact at any point on the cable will trigger an alert. The latter type is recommended over the first one due to its higher range and higher accuracy.

    If using a raised floor, then one should consider putting the sensor under the raised floor as water seeks the lowest point.

    The four main sources of water in a server room are:
  • leaking air conditioning systems: a water sensor should be placed under each AC unit
  • water leaks in floors or roof above the room: water sensors should be put around the perimeter of the room at around 50cm/3ft from the outer walls and under the raised floor.
  • leaks of water pipes running through server rooms: a water sensor should be placed under the raised floors
  • traditional flooding: same as second point for water leaks from roof or above floors applies

    The water leak sensors provided by ServersCheck can be daisy chained. This gives you a rope of up to 30m to monitor for water ingress. Need more than 30m? Simply add another sensor to your configuration. A base unit with the optional Sensorhub can support up to 8 water leak sensors for a total of 240m of leak detection. non-relevant transparent gif

    4. Implementing standards with ServersCheck' SNMP and Modbus sensors


    All sensors connect to our SensorGateway (base unit). A base unit supports up to 2 wired sensors, or up to 8 with the optional sensor hub.

    Application Location Setting Part Number Sensor Name
    Rack Level Monitoring
    Sensors to monitor intake temperatureFront - Bottom of rack for room or floor cooling, top of rack for top cooling18-27C / 64-80FENV-TEMP or ENV-W-TEMPWired or Wireless Temperature probes*
    Sensors to monitor outtake temperatureBack - Top of rack (hot air climbs) less than 20C / 35F difference from inlet temperature (typically <40C / 105F)ENV-TEMP or ENV-W-TEMPWired or Wireless Temperature probes*
    Ambient Monitoring
    Temperature & humidity monitoring in server roomsmall server rooms: center of the room data centers: potential hot zones - furthest away from airco unitsTemperature depends on type of room setup
    Humidity: 40-60% rH
    ENV-THUMTemperature & Humidity Sensor Probe*
    Airconditioning Monitoring
    Early detection of failing air conditioning unitsnext to airco units Temperature depends on setting of airco
    Humidity: 40-60% rH
    ENV-THUMTemperature & Humidity Sensor Probe*
    Water Leaks / Flooding
    Detecting water leaks coming from outside of roomAround outside walls of server room / data center and under raised floor
    best is to keep a 30-50cm / 10-20" from outer wall
    ENV-W-LEAK-COMBOFlooding Sensor Probe* with 6m/20ft water sensitive cable
    Detecting water leaks from air conditioning unitsUnder each air conditioning unitENV-W-LEAK-COMBOFlooding Sensor Probe* with 6m/20ft water sensitive cable



    As defined by ASHRAE:
    Class A1: Typically a data center with tightly controlled environmental parameters (dew point, temperature, and relative humidity) and mission critical operations; types of products typically designed for this environment are enterprise servers and storage products.
    Class A2: Typically an information technology space or office or lab environment with some control of environmental parameters (dew point, temperature, and relative humidity); types of products typically designed for this environment are volume servers, storage products, personal computers, and workstations.
    Class A3/A4: Typically an information technology space or office or lab environment with some control of environmental parameters (dew point, temperature, and relative humidity); types of products typically designed for this environment are volume servers, storage products, personal computers, and workstations.