krw wrote:
In article ,
says...
On Mon, 13 Nov 2006 14:19:07 -0500, krw wrote:
Mainframes are *not* specified for office environment (rather
"Class A") though. There is a difference between a "departmental
server" and a data center mainframe.
I am not sure what machines you are talking about but 4300s and AS400s
were office space rated. These were around before most people had ever
heard of a server or a LAN.
Ok, let me try again, slower. AS/400 and 4300s are/were what we
now call "departmental servers". /370, ES/9000s were relegated to
data centers and are rated for a "class-A" environment only. Note
that "office space" rating isn't exactly harsh either.
You guys are in semi-violent agreement.
Keith's first response was:
"Not true at all. A high RH contributes to failures in electronics
as well. Even recent equipment is specified from 40-60% RH, over a
fairly narrow temperature range."
I call the "not true at all" part complete bull****.
What Greg said was 100% true. And the gratuitous
"let me try again, slower" is another detractor.
Bottom line: human comfort and "equipment comfort"
are roughly the same, with the "equipment comfort"
range being wider than the human comfort range.
Think about it - humans operate the equipment, and
would not be willing to work in the thousands upon
thousands of "normal" datacenters if the machinerey
could not function in office-like temperature and
humidity. (Sorry - if you're in the military, you
work where they tell you - but even then, if it's
in a datacenter, it's likely to be comfortable.)
In fact, humans usually get uncomfortable outside
the 68-72 range, on average. Datacenter machinery
functions well outside of that range. The farther
you depart from that 68-72, the more extensive the
steps a human needs to take. Machines can't take
those steps, so they will fail when the conditions
are too far from nominal. What would be interesting
is some real discussion of the specific numbers.
I'll give you five examples:
1) Peat Marwick Mitchell datacenter, early 70's
An airconditioner failure caused DASD (2314) data
errors at exactly 94 degrees on their wall thermometer.
Ran fine at 93.
2) Manufacturers Hanover Trust datacenter began losing
equipment (power down) when temperature went above 90
during a blackout. (Early 80's) They had emergency
power to keep the data processing equipment running,
but nothing to power the conditioners.
3) Bloomingdales (now part of Federated) datacenter,
mid-late 70's. Red lite checks on CPU (3138) whenever
a metal cart carrying cards would touch the CPU;
random red lite cpu checks when loading paper in 1403.
Relative humidity was 16%. Raising it to 40% fixed
the problem. No hardware was damaged. Interesting -
with the lights off, when a new box of 1403 paper was
opened and fanned out, you could see the discharge.
4) Divco Wayne had a building heat failure over the
weekend. On Monday morning, the computer room was
30 degrees F. The damn system powered up and ran,
with no problems - but the 1416 print train ran
audibly slow. (Early-mid 70's)
5) IBM datacenter, early 80's. A disk pack was
transported in the trunk of a car, properly packed,
but in sub zero temperature. Upon arrival it was
immediately placed in a 2314. The idiot who did it
moved the pack to subsequent drives when it didn't
work. 180 heads, 5 VCM's and several days later,
full service was restored. I guess by the 6th pizza
oven, he moved the pack soon enough where the VCM
was not destroyed.
Specifically, the relative humidity spec is for
static/paper "fatness". The equipment couldn't
care less. It will run happily outside the range.
But if the RH is too low, static discharge can
occur, and that discharge can interfere with
equipment operation. The equipment does not mind
the low humidity, but it does mind the discharge.
"Wet" paper, due to high humidity, does not do
well in paper handling machinery in the datacenter.
Feed the equipment "dry" paper & it performs flawlessly.
I do not have statistics on "wet" paper - perhaps
one of you can discuss that in more detail.
Ed