Re: DASD failure

[John Hall <jhall@xxxxxxxxxxx>]

Tim Shepherd wrote:
> 
> Hi All,
> 
> We had a string of 9332-600's, which would fail now and again. We then had
> three go in one week, and not the same drive. We then found out from the
> IBM ce that this was a problem at a couple of sites in the immediate
> vicinity (thanks for telling us!!!). It turned out the the local "power
> distribution place" had a "floating earth" and was sending out spikes down
> the earth and bypassing our UPS. We then installed a separate earth and
> never had another problem. We then moved to an EMC Harmonix with RAID-5 and
> last year we replaced it with an EMC symmetrix disk subsystem using RAID-5.
> Since our last 9332 fell over we have had no downtime due to disk since
> then, May 1994.
> 

This brings to mind an incident we had at one of our hotel properties. 
Whenever we had a severe thunderstorm in the area we would blow out the
server.  We had UPS's on everything but just couldn't seem to stop the
problem.  There was a terminal located within the same building but on a
separate electric service.   It turns out that earth ground is not all
the "same"  Lightning would strike one "service" or even the ground (not
even our building) and the difference between the two earth grounds was
being made up by the comm cable.  Once we installed comm hardware
designed to go between buildings we never had another problem !

Everything about the electric service on our property was up to code and
installed correctly.

John Hall
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