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Tuesday, June 17, 2008

Temperature monitoring in a server room

A question we often get from customers is: "how many sensors do I need?"

The actual question a customer needs to ask himself is: "how much do I want to spend on environmental monitoring?"

The basic monitoring is temperature. In later posts we will explain the benefits of other types of monitoring.

There are 2 main types of temperature monitoring:
- ambient temperature monitoring
- rack temperature monitoring

Ambient temperature monitoring is capturing the temperature in the room the same way you feel it when you are standing it. It is the temperature reading used by air conditioning units to operate.

However it is not the temperature in which your systems operate. In a number of server rooms we visited each time we could sense so called "hot zones". These are area's in the room where it is much hotter compared to others; often due to either layout of the room (cornered) or type of equipment (ie heavy server concentration in one area).

The problem with ambient temperature is that it takes some time to increase above a treshold when an issue arises in one particular area. If you are sitting in front of a fire place, it will be way warmer than in the rest of the room; especially when the room is larger. Same applies here.

In order to detect issues faster, one solution is to put every 3-5 meter or 10-15 ft a temperature sensor.

Best practice however is to monitor each rack individually with one sensor per rack. Using our IP based sensors, the sensors are positioned at the rear of the rack and near the top. Remember your physics class in high-school: hot air climbs.

The more sensors you deploy the earlier you will detect an issue.

However just one sensor in a room is far better than doing nothing.

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