[Nut-upsdev] Documenting the NUT driver-qualification process

Ted Mittelstaedt tedm at mittelstaedt.us
Wed Jul 9 16:26:08 UTC 2014

On 7/9/2014 3:31 AM, Eric S. Raymond wrote:
> I think the time for me to get involved in NUT documentation has come
> again.
> Late last week I had to buy a UPS under time pressure.  The Eaton unit
> that thus project gifted me with in 2006(?) died during a severe
> thunderstorm watch, so it was off to MicroCenter to get a replacement
> pronto.
> I wound up buying an APC BN700MC.  It was what they had in the
> performance range I needed.  The removable battery door was pleasing.
> Based on the experience, I have updated the UPS HOWTO:
> http://www.catb.org/esr/ldp/UPS-HOWTO.html

There are some other things in that FAQ that are wrong, they are as follows:

"...The aging power grid in the U.S. has made this a more urgent issue 
than it used to be even for American hackers..."

Pure rubbish.  The following study says the grid has been unchanged
for events below 2000MW and only slightly increased for events above that:


Of course, there are those who have flat-out lied about this study:


"...increase during the period from 1984 to 2006. That is the main 
conclusion of a working paper, published last January, by the Carnegie 
Mellon Electricity Industry Centre..."

The paper they cite DOES NOT SAY it is the "main conclusion"

The fact is that multiple public agencies (like NERC) are attempting to 
gain more funding in the United States - this is what bureaucracies do 
after all, is try to get more money.

So they do these studies and find a slight change then bang the gong
running around saying the sky is falling.

Eric, consider that global warming has increased the power and frequency
of storms in the US over the past 20 years - we have had more tornados
and hurricanes than ever which have destroyed more stuff - and there is
a far, far greater correlation between that and outages, then any
"insufficient spending" arguments that people like Massoud Amin who go
on NPR and make noise would have you believe.  Dr. Amin completely
ignores storms in his analysis even though those are the largest cause
of blackouts.

If you feel compelled to Chicken Little your FAQ than change it to:

"...Global Warming and the increased storms it causes have made this a 
more urgent issue than it used to be even for American hackers..."

Then at least your Chicken Litteling it for a REAL reason not acting
as an unwitting participant in some political scheme by a government 
bureaucracy to make a money-grab.

"An important fact about surge suppressors is that they need to be 
replaced if they absorb a large surge. Besides fuses, most suppressors 
rely on on components called Metal-Oxide Varistors (or MOVs) for spike 
suppression, which degrade when they take a voltage hit. The problem 
with cheap suppressors is that they don't tell you when the MOV is 
cooked, so you can end up with no spike protection and a false sense of 
security. Better ones have an indicator"

The indicator is a power indicator there's no way to build an indicator
that tells if the MOV is cooked or not.  Any indicators you see are
"feel good" indicators.

I personally think MOV's degrade over time due to the plethora of SMALL
spikes they absorb, but I have seen NO data on this one way or another.
This would be a great thesis or graduate study for an engineering 
student to do.

"The basic principle is this: ZS units slow down the surge with a 
network of passive elements and then sends it back out the neutral line"

Too much watching of Star Trek there.  The transformer in a conditioner 
protects against a surge because a surge is so brief it is far higher 
frequency than the transformer is able to resonate at - in short the
transformer simply does not work for the high frequency spikes and
surges it only works for the low frequency AC power.

" in these days of journalling filesystems like Linux's EXT3 or JFS from "

Who still uses ext3?  I think you mean EXT4.

"UPSes are nowadays very inexpensive. In the U.S. in 2006, quite"

change the date there

"by things like the size of monitor you use (big ones can be quite 

big ones with tubes in them - we are all using flat panels now...

"My advice is to forget the numbers game. Just go online or to your 
local computer store and buy one of the higher-end consumer or SOHO 
models from APC, CyberPower, Eaton, Tripp-Lite, Belkin, or some other 
reputable manufacturer. Go ahead and grab the model with the longest 
dwell time, highest watt rating, or biggest VA number you can find; the 
premium for it is not likely to be more than US$75 over the 
bargain-basement model"

APC BackUPS models under the 700 level NO LONGER contain a monitoring 
port. You need to be careful when advising people what UPS to buy to 
tell them to look for this port.

"Do not buy a serial line UPS (one that communicates via an RS-232C 
cable). These are passing out of use in favor of UPS designs that use 
USB or Ethernet, for the very excellent reason that RS-232C interfaces 
are flaky"

Serial is passing out of use because Microsoft and Intel said to stop
using it in the PC 2001 standard:


where (for cost reasons) they strongly emphasized Legacy Free PCs'.


It has absolutely nothing to do with flakiness of RC232C.  The reality 
is that RS232C when properly implemented per the standard is NOT flaky.

You could say that 100foot USB cable is flaky - because it is - because 
it's a gross standard violation of USB - are you then going to label USB
flaky because some bozo isn't implementing the USB standard properly?


> The bad news, however, is that (a) this is not a NUT-supported device,
> and (b) the (poorly documented) NUT process for discovering and
> customizing a driver failed at the first step.  Running upsstart
> gave a driver fail message containing no clues as to how to recover.
> This is definitely USB and probably a fairly generic hidups device.

> There is no good reason for customizing a driver profile to be
> so difficult.
> What I'd like to do is this: confer in real-time, perhaps via IRC,
> with someone who knows this process.  Ask about every step (thought
> processes and diagnostics).  *Write them down* and turn this into a
> document on how to qualify and support a new device.
> Volunteer, please?

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