[nSLUG] linux home or workplace automation and Universal Powerline Bus

George N. White III gnwiii at gmail.com
Sat Sep 20 16:15:13 ADT 2008


On Sat, Sep 20, 2008 at 3:29 PM, Ian Campbell <ian at slu.ms> wrote:

> On Sat, Sep 20, 2008 at 02:52:09PM -0300, George N. White III wrote:
>> 2.  with a short period (1-2 mins), initiate shutdown of the
>>      lower priority systems -- a) they don't get generator
>>      power so will have to be shutdown, and b) to reduce
>>      the heat going into the room
>> 3.  if the generator comes on, start the A/C after the
>>      specified delay, otherwise, initiate shutdown of the
>>      remaining systems so they can do a clean shutdown
>>      before overtemp is triggered or the UPS dies.
>>
>
> Invest in lower-power gear. Lighter cooling needs, lighter power draw.

I wish!

The numerical modellers buy as much compute power as the mains
will allow and the floor will support, so it has become f.p. operations per
watt that matters.  At present, many numerical models getter better each
time you add CPU power and remove simplifications made in version N-1
to lower CPU requirements.

Also, much of the software used in remote sensing today was designed
for the computers we had in the 1980's.  Newer sensors were designed
in 2000, but the computing requirements were (by design) extrapolated
to 2008.   With the 1990 computer, it took a year to reprocess a year of
data.  WIth the 2000 computer, that was down to a month, but we had
more years of data.   With the 2008 computer, the same reprocessing
takes days, but there are more years of data from more satellites,

There is, however, a big change in how I think about reliability.  When
each individual job took a week, you really couldn't afford to have jobs
die every time the lights in NS go out.  Now that individual jobs take
minutes, you might be able to afford some stoppages, but updates
to data files and software are coming more often than power outages,
Applying patches for security and stability has become the largest
category for downtime.

Unplanned shutdowns tend to require lots of manual work to sort out
which jobs need to be re-run, etc.    The software falls back to lower
quality data sources if it fails to get the "best" available version
via internet.
This is done so you get the best product possible at the moment the
calculation is done, important for some uses, but means many calculations
have to done several times as various input data streams are revised
and broken web sites come back online.

-- 
George N. White III <aa056 at chebucto.ns.ca>
Head of St. Margarets Bay, Nova Scotia



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