30/03/2021

How to Monitor Data Centre Environments and Infrastructure Systems

Server rooms and data centres are designed to provide secure, managed, and controlled environments in which to run IT operations. In order to ensure uptime and availability, it is importance to have a suitable environmental monitoring system in place but what should you monitor and how should the data collected be reported and acted upon?

What is an Environmental Monitoring System?

Environmental monitoring systems consist of a data logger that collects information from connected sensors and uses this to initiate alerts when measured data falls outside of pre-set parameters. A monitoring device can range from a 1-2 sensor port device to more expansive units with up to 10 or more (RJ45) ports to which multiple sensors can be connected using a 1-Wire UNI bus. The monitoring devices can be designed for installation in a 19inch server cabinet, either as a rack mount, shelf, or DIN-mounted unit and are powered either by a plug-in AC/DC power adapter or Power-over-Ethernet (PoE) via one of the RJ45 ports.

Plug-in Environmental Sensors

The most used sensors are for temperature and humidity. These environmental factors can be monitored using single cables (one for temperature and one for humidity) or combination cables that can monitor for both parameters.

Temperature monitoring is the number one factor monitored in server rooms and data centres. A rising temperature can indicate a failure in the air conditioning and cooling system. Thought it might not be detrimental to the overall IT operations, an increasing room ambient will itself lead to cooling systems using more electricity as the cooling load increases. This will increase data centre energy efficiency metrics such as Power Usage Effectiveness (PUE).

The ideal temperature for a server room or data centre is 18-25⁰C. Below 18⁰C is not a comfortable working environment for engineers and technicians in a server room or data hall. The same applies for temperatures above 25⁰C but there are other implications. High room ambient temperatures can start to impact component lifetime.

An example is the valve regulated lead acid (VRLA) battery used in the majority of data centre UPS. For every 1⁰C rise above 30⁰, their design life halves. Most lead acid UPS batteries are either 5-year or 10-year design life batteries and they are costly to replace, especially when earlier than budgeted for. Lithium-ion batteries are more temperature tolerant but can have a 20-30% price premium over lead-acid UPS batteries.

Humidity is the second most monitored aspect within a server room or data centre. The ideal humidity level is between 40-60%. Humidity level is a measure of water content or vapour in the air. If the humidity level is too low, then static electricity can build up, leading to electrostatic discharges (sparks). If too high, condensation can occur when cooled high-water content air meets warm surfaces and condensates, leading to water droplets that could run down and into an electronic or electrical device. High water content can also lead to metallic corrosion and even mould.

Humidity is again controlled by the air conditioning and cooling system. Low or high humidity levels indicate a potential issue that should be investigated. Whilst it is natural to assume the cooling system needs adjustment or preventative maintenance, higher humidity can also be a result of water leakage into the date centre space (from a flood plain or burst water pipe) or a change in the air outside a building i.e. before a summer storm.

The third most-commonly monitored environmental factor in a data centre is water leakage. This can be done with two types of sensors. A spot-sensor that has a small sensor device fitted to a cable and will measure for water droplets in a single spot or a water-leakage rope sensor that will monitor for water-leakage along its length. A spot sensor can be used underneath an air conditioner for example. If the air conditioner generates water droplets, they could fall into a drip tray and indicate issues with the cooling unit i.e. a blocked filter. Water leakage sensor cables can run from 1-2m up to 30m or more using extension cables. The cables themselves are extremely sensitive to liquid droplets and can typically be washed and dried for re-use following a water-leakage incident. Water leakage rope could be run around the perimeter of the IT space.

Other sensors that could be deployed within an IT environment include air quality, air pressure and air flow. Air quality sensors can be installed for carbon dioxide, particles, and volatile organic compounds (VOCs). Air pressure and air flow sensors can help to detect whether cooling systems are delivering the calculated levels of cooling to and within the server rack space. Air flow sensors can provide additional monitoring of air conditioner outputs. If the air pressure and/or air flow is too low, then cooled air may not reach the intended area(s) within a server room or data centre or the server rack cabinets within them.

Plug-in Detectors

In a server room or data entre monitoring system, detectors can add another dimension. Detectors can monitor for smoke, fire, motion, room or server rack door entry, power presence, gas leakage, UPS battery status and fuel level in generator fuel tanks.

Whereas sensors provide analogue data that can be analysed, detectors provide digital input (DI) signals using dry-contact (volt-free) relays where the status ON/OFF indicated OK/Not OK. When the signal is picked up by the environment monitoring device, an alarm or alert is raised. Detectors tend to be connected to the monitoring device using hardwired terminal connections.

Some environmental monitoring devices also incorporate digital outputs (DO). This allows for logic-based commands to be issued when there is an alarm condition raised, either from a sensor or detector. For example, when an alarm signal is generated, a relay could turn on an audible buzzer or light beacon or a motion sensor camera activated.

Data Centre Monitoring Software

For accurate data logging and acquisition, you must have the right sensors and detectors in the right places within your server room, data centre and even within your server racks and cabinets. However, as important is the software platform used to provide dashboard and alarm related information.

Most environment monitoring units have a web interface, allowing information to be gathered using a HTTP/HTTPS browser. Local Ethernet RJ45 ports or Wi-Fi connectivity will connect the monitoring device to the local IP network from where information can be viewed in one of three ways.

Each environment monitoring device manufacturer will generally provide a software package that can be downloaded from their website and run on a local area network. They may also provide a cloud-based portal for accessing the monitoring device and its data over an internet connection. As well as providing dashboards and graphing sensor/detector related information, the software will also provide facilities to create email alert distribution lists. SMS text messaging may also be possible, as may voice calls. A third method involves providing information via SNMP and MIBs for third-party monitoring platforms including SolarWinds (https://www.solarwinds.com/) or PRTG (https://www.paessler.com/).

Wireless Connectivity

Using the local secure Wi-Fi network provides a way to deploy sensors and detectors throughout a large data centre without incurring additional cabling and hub connection costs. Whilst this practice may not be considered suitable for some data centre operators, wireless monitoring devices could become more widely used for Internet of Things (IoT) and Industrial Internet of Things (IIoT) applications as 5G mobile rolls out. A wider adoption of wireless connectivity will also push down overall cost-per-port monitoring for server room and data centre operators.

Summary

It is relatively straight forward to install environmental monitoring into a computer or server room. Typically, 1-2 sensors may be all that is required due to the size of the room. In a data centre, more thought must be given to the design, both in terms of the scale, location and number of sensors and detectors required.

In a server room, the software supplied by the manufacturer of the environmental monitoring system is typically used to provide dashboard views, alarm monitoring and alert notifications via email and/or SMS. In data centre environments, sensor data may be collated to provide more complex heat maps of the room and within each individual server cabinet. The data may also be reported to a more comprehensive data centre monitoring infrastructure monitoring (DCIM) platform using SNMP.

Whether you are looking to monitor a server room or a data centre environment, the basics of environmental monitoring apply. Look at what you need to monitor, where and how, and install suitable sensors and detectors and collate information in real-time that can be analysed and used to initiate alarms to distribution lists for actions to be taken to ensure continuity and uptime.

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