I have just come across a data center with a rotary UPS today. What does r/sysadmin think about them compared to battery UPSes? Would this cause any red flags if you were looking for DC space for yourself?
Posted May 6, 2020, 9:16 PM UTC
Huh interesting, never heard of a rotary ups ... pretty cool!
According to this link below, it seems like rotary UPS are implemented when there are "multiple short inrushes of power" such as satellite and broadcast stations or for high security installations. .... Not sure what makes it high security yet lol.
Maybe give it a read through and see if it helps.
I know right? I thought I heard of most things when it comes to data centers but this is something I only learnt today! Needless to say I have been doing some reading up since learning this.
The tech is sound and I'd have no problem using them as a DC customer or directly. However, a 365 Main power failure in 2007 was attributed to bad behavior/firmware on the flywheel backup power:
The 365 Main data center is supported by 10 Hitec 2.1 megawatt generators, which are tested every month. The 277,000 square foot 365 facility is partitioned into eight data center “pods,” some of which remained online while others went dark.
The facility’s backup systems use flywheel UPS systems - rather than batteries - to provide “ride-through” electricity to keep servers online until the diesel generator can start up and begin powering the facility. A flywheel is a spinning cylinder which generates power from kinetic energy, and continues to spin when grid power is interrupted. In most data centers, the UPS (uninterruptible power supply) system draws power from a bank of large batteries. AboveNet, the original builder/owner of the 365 Main data center, was an early adopter of flywheel UPS systems, which have recently gained attention as a “greener” alternative to batteries.
Some customers speculated about a flywheel issue. Trouble shooting the exact reason for the generator failure will take some time, according to 365 Main. “Due to the complexity and specialization of data center electrical systems, we are currently working with Hitec, Valley Power Systems, Cupertino Electric and PG&E to further investigate the incident and determine the root cause of why certain generators did not start,” the company said in its incident report.
The downtime quickly became a public relations setback for 365 Main, as the blogosphere pounced on a failure that knocked many of its leading hosts and services offline. The outage was highlighted at O’Reilly Radar, Scobleizer and TechCrunch, among others.
Earlier in the day the company issued a press release noting two consecutive years of uptime for a customer at the San Francisco data center, RedEnvelope. The press release was noted on Slashdot and Techdirt and has since been removed from 365 Main’s web site.
Misinformation spread swiftly, propelled by the blogs and forums not affected by the outage. CNet, which hosts its servers at 365 Main, debunked reports from ValleyWag that a drunk employee had gone on a rampage and that a “mob of angry customers” assembled outside the 365 Main building. The “mob” was actually a line of customers who were forced to enter through the front door and have badges checked manually to get into the building because the parking garage gate was affected by the power outage, according to CNet. ValleyWag’s “drunk employee” post quickly became one of the most popular posts on the front page at Digg.
The problems began when parts of PG&E’s San Francisco area network began experiencing voltage fluctuations, which apparently caused a transformer to fail in a manhole under 560 Mission St. Witnesses told the San Francisco Chronicle they heard a blast shortly before 2 p.m. and then saw flames licking up through the manhole grate. PG&E could not confirm that an explosion had occurred, but said that 30,000 to 50,000 customers were affected.
The 365 Main data center was originally built by AboveNet, which spent $125 million to construct and “earthquake proof” the facility. After AboveNet filed for bankruptcy, 365 Main bought the property for $2.6 million in a court-approved deal. 365 Main has since expanded its network to seven data centers, including facilities in Oakland, Phoenix, Chantilly, Va. and two centers in Los Angeles (El Segundo and Vernon/Irvine).
They provide the magic number of "about 10 minutes" of power that you need because your ATS fails every time and you have to manually switch to the generator. The downside is that you cant really overbuild a flywheel like you can a UPS. For instance Eaton just swapped our batteries with new ones and now it will run for 90 minutes with the same load.
Really appreciate this perspective! This is about the number that was quoted, and they said due to this their generator design has to start up quicker. I am slightly wary because I have never of this before honestly!
Yeah well I have been responsible for all parts of a datacenter for about 22 years and when the utility fails having extra time to 'mess around with' the transfer switch before the batteries discharged fully has saved us at least 5 or 6 times. Transfer switches are the least reliable part of a DCs power infrastructure.
Flywheel gensets don't require transfer switches to activate, though, because they're in-line with the circuit and spinning constantly.
There is a transfer switch somewhere. between the a&b utility feeds.. etc.