Background: The server I’m configuring needs to be able to work at altitudes up to 10,000 feet.
Are there any rules of thumb or guidelines on how much faster fans have to spin at altitude (due to lower air density) to provide adequate cooling? Or if I know that my server’s fans are going at 50% at sea level, what % will they be running at 10,000 feet?
Are you talking 10,000 feet in a pressurized airplane, or in the raw environment?
If you mean in a pressurized airplane this is a moot point. Normally those environments stay pressurized at a level “below” 8000 feet.
If you mean the raw environment You’re talking about roughly a 4.6psi decrease from sea level (-32%) – but bear in mind that you’ll also be in a substantially colder environment (about 2 degrees (C) cooler for every 1000 feet). The decrease in volume of air moved by the fans should be compensated for by the temperature drop.
Of more serious concern should be ensuring that all components (hard drives, etc.) are rated to operate at that altitude – having your server die because there’s not enough air to build an “air cushion” for the hard drive heads could ruin your whole day.
At one time it was pretty common for equipment to list a maximum operating altitude (which was usually 10,000 feet) – you may want to check with your vendors.
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