Mailinglist Archive: opensuse (2496 mails)

[Erland Moller <erland@xxxxxxxxxx>]

James Knott schreef:
> Randall R Schulz wrote:
> > On Monday 01 December 2008 08:31, James Knott wrote:
> > > Randall R Schulz wrote:
> > > > Hi,
> > > >
> > > > Seeing the recent mention of UPS (on the thread "Of software RAID
> > > > on SUSE Linux") a question came to mind:
> > > >
> > > > If you have multiple computers, how does one get them to all
> > > > initiate the desired actions when main power fails and the UPS
> > > > takes over?
> > > >
> > > >
> > > > Randall Schulz
> > > ...  Of course, with the cost of a UPS these days, why not have one
> > > for each computer, especially since the more computers you have on the
> > > UPS, the shorter time it will support them.
> >
> > I thought of that, too, but presumably any given amount of energy 
> > storage is going to cost less if it comes in a single package with a 
> > single set of the other (non-battery) hardware, right?
>
> In theory.  However once you move into a larger UPS, you move out of 
> cheap consumer level devices.  Industrial quality costs a lot more.  
> For example, my employer sells a 1000 VA UPS for $228.  For that 
> amount, I could buy 3 550VA or 2 750 VA units at the local office 
> supply store. At that same store, a 1000 VA UPS sells for more than 
> twice what we charge.  Of course, running multiple computers off the 
> same UPS requires they be close enough to do so.  You can of course 
> get much larger systems, to support an entire office, but then you're 
> talking a *LOT* of money. (Last year I was at one site that had a IIRC 
> 300 KVA UPS to power a police headquarters communications system.)

Don't forget that with a bigger/more expensive UPS, most of the time you 
have the advantage of hot-swappable battery's and/or a bypass function 
plus the ability to shut down more than one server if things go wrong.
Most of the small UPS's have to be shut-down to swap the battery's. 
Furthermore with the big UPS's the battery voltage is higher resulting 
in low amp's on the battery's resulting in longer lifetime.

Greets,
Erland.

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