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Comment by cm2187 | Hacker News Reader

Why would backup generators be running outside of power cuts? Even if it is just to test them, that should only be a minute from time to time.

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They're not. This story isn't very good. The point it makes is somewhat valid, but the reporter's lack of understanding on the details means the way the story is written doesn't provide much insight.

Likewise, I'm guessing "utilization" is measured by taking a loadavg, which is... not exactly really a complete measure of utilization.

Well they could be.. Demand Side Response is a mechanism where utility companies pay energy consumers to stop using grid power at peak times. Effectively a company is treated as a power generator but instead of selling power to the grid they just consume less either by turning stuff off or relying on on-site power generation for a while.

It's popular in lots of industries but there seems to be relatively little (publicised) adoption in the data center business yet.

The growing datacenter trend is to build dedicated co-generation facilities (typically, with the power company footing half the bill because you're doing them a favor and taking load off of the local grid).

In the US, generator power is considered dirty, and only meant to be run on during emergencies. Running generators during not-emergency times will typically get you a nice call/visit from the state's environmental agency courtesy of your complaining neighbors. Said agency will ask you to curtail your usage to no more than X hours per month.

In the UK, DSR consists of you entering into a contract with National Grid, one or four years in advance, to produce energy during peak times (not just "reduce usage") at an auctioned rate, but pay a stiff penalty if you fail to deliver. Plus, you're not allowed to participate in back to back years.

They could be doing peak-shaving. Sometimes when your electricity usage heads into a new price tier it becomes cheaper to generate power yourself by burning diesel.

Another possibility is demand-response. Some utilities also offer incentives to customers who can voluntarily take some of their load off the grid during times of high demand.

For the regular tests I know one Telco DC that used to run daily tests of its generators.

Because when the power does cut, how long is it going to take to get those generators up and running? It's not like the whole place can run on a battery backup in the meantime.

Seconds or less. This is a solved problem.

Backup uninterrupted power is not typically done by keeping generators online 24/7.

No.. the whole place DOES run on battery backup while the generators start. A large data center will have multiple rows of these: https://en.wikipedia.org/wiki/Data_center#/media/File:Datace...

Done right the DC is always running off battery the backup gensets are there to replace the mains power.

Generator take anywhere from 7-15 minutes to spool up and produce power.

So every (serious) datacenter has rows and rows of batteries to cover the lag time between power loss and generator start-of-service.

Not if you get good generators and the systems on standby. On an oil rig our engines always have their lube oil prelube running and heaters on. We can go from blackout to online in under a minute. Like most other things it's an engineering problem and how much money you're willing to spend to solve the problem.

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