Datacenters need cool dry air? <45%

No, low isn't good perse. I worked in a datacenter which in winters had less than 40%, ram was failing all over the place. Low humidity causes static electricity.

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swiftcoder 6 hours ago | parent | next [-]

The datacenter is in San Diego - a quick Google confirms that external humidity pretty much never drops below 50% there.

Things would be different in a colder climate where humidity goes --> 0% in the winter

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mbreese 8 hours ago | parent | prev [-]

Low is good if you are also adding more humidity back in. If you want to maintain 45-50% (guessing), then you would want <45% environmental humidity so that you can raise it to the level you want. You're right about avoiding static, but you'd still want to try to keep it somewhat consistent.

It is much cheaper to use external air for cooling if you can.

	▲	hbogert 8 hours ago \| parent [-]
		Yeah but the article makes it sound as if lower is better, which it is definitely not. And yeah you need to control humidity, that might mean sometimes lowering, and sometimes increase it by whatever solution you have. Also this is where cutting corner indeed results in lower cost, which was the reason for the OP to begin with. It just means you won't get as good a datacenter as people who are actually tuning this whole day and have decades of experience.