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

On 8/2/2010 7:56 PM, James H. H. Lampert 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,

You live a charmed life! I cannot count the number of power supplies that I have seen or been in the presence of failing on AS/400, iSeries, and Power systems. When power supplies fail and there is only one bad things happen. This is not to say they are unreliable but behind disk units power supplies are the most common failure item in my years.

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.

This is correct. Dual power cords do allow for connection to separate AC Supplies. MOST of my customers who do so feed the supplies from separate UPS units both of which are sized to carry the entire system. This way they are protected from AC power loss as well as complete UPS Failure. At least one of the UPSs is usually backed up by a genset.

Unlike your experience excepting that 'thing' IBM sold with the 170s of years past I've not had any sort of issue with UPSs as you have. I have seen UPS Failures but they have been VERY long in the tooth units (in one case from the S/38 days) that soldiered on far far past it's designed life span.

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).

Absolutely this is a good thing to know without question. To monitor such things independently however I wouldn't do this on i, I would do it with something such as the Web600 from sensaphone. It monitors six things, (you pick temp, power, current etc) has an optional backup battery and can email you, or otherwise notify you when any particular event occurs. Power outage, Temp exceeded etc. That's what hangs in the FrankenLab.

- Larry

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JHHL