> Yup. Related: "100% availability" is a marketing person's dream; it
> sounds good in theory but is unattainable in practice, and is a
> reliable sign of non-100%-reliability.
You are confusing two different things.
No, I'm not. They're interrelated. That doesn't mean that they are
the same thing, but to talk about them in terms of their relationship
or their effect on service is perfectly fair.
> And even for those who follow best practices... You can inspect and
> maintain things until you're blue in the face. One day a contractor
> will drop a wrench into a PDU or UPS or whatever and spectacular things
> will happen.
That's were policies, procedures and methods come in (read: SAS70)
Policies, procedures, and methods are nice. Unfortunately, it is not
too uncommon for all of the above to be bent or broken for a whole
slew of reasons. What about a problem that hasn't been planned for?
It only takes one time ... one mistake ... of just the right kind.
> Or a battery develops a strange fault.
Get more than one string, one more than one UPS, with monitoring.
Batteries are NOT the Achilles heel everyone wants to make you
believe they are.
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.
... JG
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)
another vendor is Active Power (which i think partners with cat)
They seem to be MUCH more reliable than batteries from what i read
HE probably acquired one of those solutions
-Raphael Carrier
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 flywheels,
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.
Owen
Speaking as an individual, not representing any affiliation.
Yup, just ask 365 Main how reliable they are -
http://365main.com/status_update.html
I'm not saying that battery-based UPS's are better, but no matter what type
of system you look at you're going to find failures.
Scott
Sry for the top post...
As more facilities are built/retrofitted with an eye toward overall efficiency using CCHP, we will start seeing more facilities (like Syracuse U's new datacenter) use systems like the Capstone turbines for primary power/secure power/CCHP. The main grid will become the backup. Not saying this approach replaces the need for batteries or some other storage device such as a flywheel system..
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