HE.net, Fremont-2 outage?

Owen DeLong owen at delong.com
Wed Nov 4 22:18:04 UTC 2009

On Nov 4, 2009, at 2:08 PM, Raphael Carrier wrote:

>> I know you have a rather higher faith in batteries than some of us,
>> but practical experience suggests that batteries are merely a mostly-
>> reliable technology.
> Agreed batteries are unreliable, an alternative to battery based UPS
> are flywheel energy storage devices, they come either as an integrated
> solution with the diesel generator (i think cat offers such a package)
> or as a standalone UPS (see:
> www.pentadyne.com/uploads/18/File/Pentadyne-VSS-Brochure.pdf)

Apparently you do not remember 365 Main...

Batteries are reliable.
Flywheels are reliable.

Both require proper maintenance and proper procedures to handle
corner cases (like the multiple-outage corner-case that took out
365 main).

Both have their issues.

In my experience working at and with a variety of datacenters, I have
to day that I have had generally better luck with batteries than  
but, the key difference that suggests flywheels could actually be better
technology is this:

About 50% of battery failures traced back to human factors.

100% of the flywheel failures I experienced were human factors related.


Speaking as an individual, not representing any affiliation.

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