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The BIG EEVblog Server Fire

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james_s:

--- Quote from: floobydust on April 12, 2021, 02:15:51 am ---I looked at google street view and only one exhaust pipe for a generator, near the electrical room.
The facility appears to be in some old warehouse (military?) district with brick exterior walls and a wooden roof? If true that's a problem.

Had to laugh, not a solar panel in sight.

--- End quote ---

Buildings like that are all over the place in light industrial areas. As I mentioned my friends have a machine shop in a similar building, they've had all sorts of different neighbors and they've moved a couple of times too. Auto mechanic, sign company, importer warehouse, cabinet maker, in their current spot the place next door sells and services air compressors, that kind of stuff. In most of these industrial parks the business rents one or more bays and outfits the interior as needed. Solar probably isn't really an option in most of those places, they don't own the building and the landlord doesn't care about the power bill, they aren't the one paying it. They don't want a bunch of holes drilled in their roof.

schmitt trigger:
Very interesting thread!

As I mentioned previously, hopefully Dave will do a video(s) regarding the subtle details of ensuring AC mains uptime.

With everything nowadays tied to the web, this issue has become more critical than ever.

Back in the mainframe days, I remember a motor-generator set where the blackout ride-through energy was stored in a gigantic flywheel.
To my surprise, they are still being used.
Google has plenty of examples.
.

duckduck:

--- Quote from: NiHaoMike on April 12, 2021, 03:04:00 am ---How much can the backup power infrastructure be cut back if there's a system to force all CPUs to minimum frequency when running on backup power?

--- End quote ---

That's a great idea. One issue I can see for a hosting company is that they allow their customers to manage/reinstall to OS and apps. It would be difficult to enforce the installation of power-management software. It would be great if servers had a (let's say) 5 volt input, and when it dropped to below 1 volt, the BIOS would throttle the CPU down. Then you "just" run a 5 volt line run off of non-UPS, non-generator mains to each server and you're golden.

schmitt trigger:
In the rotary UPS I mentioned above, it was explained to me that during the elapsed time between mains interruption and the diesel genset actually supplying power, certain non-critical processes were halted. Like printers and punched card readers.
There may have been others.

bd139:

--- Quote from: NiHaoMike on April 12, 2021, 03:04:00 am ---How much can the backup power infrastructure be cut back if there's a system to force all CPUs to minimum frequency when running on backup power?

--- End quote ---

That probably wouldn't work. If you're running near your CPU provision, you can enter a thing called "load hysteresis" which may be irrecoverable. This is where your load average goes above the total capacity and the CPUs can never catch up with the workload.  It requires adding much much more capacity than you had to start with before you can being the demand you had originally. Either that or breaking a huge chunk of your incoming load to recover.

This is similar to halving the size of your cluster during peak demand, which never works out well. I was working for a very large stats company here a few years back and there was a sudden spike of packet loss over the inter-DC link they were running. The ops director at the time decided to fail the active-active over to active-standby and caused a 5 minute chunk of slowness into a 4 hour recovery job.  :palm:

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