Re: Monitoring for power outages on a dual-powered system

At a former employer, we lost like 3 or 4 power supplies in one of our
routers shortly after moving from an 825 to an 810 and in the process
cleaning out unused twinax and other cables from underneath the raised
floor.

About a year later, at my current employer I ran across the NASA paper
about "zinc whiskers" which is what Rob is talking about.

Google "zinc whiskers" for more info...

Charles

On Wed, Aug 4, 2010 at 9:20 AM, <rob@xxxxxxxxx> wrote:

James, I have lost over 6 power supply units on IBM i and it's
predecessors.  Most of these had to do when I replaced our raised floor
panels and some electrical phenomenon called zinc threads.  Bizarre was
when I was asked by IBM over the phone if I was changing my raised floor
panels.  I wondered how they knew and the gentleman said that was the only
other time he heard of something like this.

Not all of these had to do with this though, some just died at other
years.


Rob Berendt
--
Group Dekko Services, LLC
Dept 01.073
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





From:   "James H. H. Lampert" <jamesl@xxxxxxxxxxxxxxxxx>
To:     Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Date:   08/02/2010 07:58 PM
Subject:        Re: Monitoring for power outages on a dual-powered system
Sent by:        midrange-l-bounces@xxxxxxxxxxxx



Simon Coulter wrote:

Of course there is. Redundant power supply units are to protect
against failure of one power supply unit.

This is POSITIVELY THE LAST THING I WILL SAY ON THIS:

1. In over sixteen years of experience with IBM midrange systems, I have
never, once, seen an internal power supply unit fail. On the other hand,
A. I have seen line power fail multiple times
B. I have seen UPSs from two different manufacturers fail with
absolutely no advance warning whatsoever
C. I have seen UPSs send "On Battery Power - battery nearly dead"
messages through the monitoring cables, during self-tests, on more than
one occasion, when there wasn't a damned thing wrong with the line power.

2. If, as you say, multiple redundant power supplies were not intended
to be plugged into separate power sources to guard against one of the
sources going down, THERE WOULD BE NO REASON FOR TWO SEPARATE AC CORDS.

The question is about monitoring for one or the other power source
cutting out at a time when nobody is here to notice, NOT monitoring the
UPS itself (which we do NOT do, PRECISELY because item 1C has occurred
on multiple occasions).

--
JHHL
--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing
list
To post a message email: MIDRANGE-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/midrange-l.


--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list
To post a message email: MIDRANGE-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/midrange-l.