If a server within a data centre isn't being utilised, then powering it down may seem like a sensible move. However, an inactive server can have an unexpected impact on your overall data centre running costs, since it can still be a conduit for air which can cause unexpected pressure management issues.
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A study into server airflow conducted by Tate found that in a 42-unit rack running in conjunction with cold aisle containment, airflow through the individual servers could still result in 775CFM of air pressure leakage. That can create problems.
Tate conducted the study after a customer noticed that it was experiencing unexpected pressure issues in a data centre utilising cold aisle containment for heat management. "When they would close the cold aisle doors, the aisles would reach a relatively high pressure that made it relatively difficult to close the doors," Tate senior sales engineer Daniel Kennedy said during a presentation at Data Center World in Las Vegas.
"In a cold aisle system, it's probably beneficial to remove servers as soon as you shut them down," Kennedy said. "It's important to remove equipment and replace it with blanking panels as quickly as possible, because there's no good solution to the leakage issue. If the whole rack is off, you can also blank the door." Built-in dampening systems that restrict airflow when a server is not in use are another possibility, but haven't yet been introduced and could cause other reliability issues.
In practice, it's almost impossible to ensure that server racks are entirely sealed. "It's very difficult to maintain a hermetic seal in a rack environment," Kennedy said.
While CFD modelling tools can incorporate leakage into their calculations, finding data on leakage rates for individual servers can be difficult. "It's going to become more of a problem as we get better at using the equipment we have," Kennedy said.
Lifehacker's World Of Servers sees me travelling to conferences around Australia and around the globe in search of fresh insights into how server and infrastructure deployment is changing in the cloud era. This week, I'm in Las Vegas for Data Center World, looking at how the role of the data centre is changing and evolving.