Re: (OT) Storage (8*IDE HDs) any experiences?
Dell Poweredge 2450 style servers is what you're looking for. They have
two power supplies, each with its own power cord. Yes, it can run on one
PS... the last one I set up ran that way on my desk since I only had one
cord handy. Of course, you'll want to make damn sure the grounds are at
the same potential, so doing funny tricks with where you plug them in
could be a bad idea.
Another nice thing about this (and probably all the machines Matthew's
referring to) is that the motherboard doesn't need to "support" multiple
supplies, nor do the hard drives, fans, tape drives, etc.
I agree with Matthew in that there _is_ a reason to share the load,
actually a few that I can think of. Let's say you have a pair of 300W
supplies on a box that draws 250W at rest. Rather than let one supply
crank along at 250W, let's let both supplies run at about 125W. That
way, both supplies will run cooler (Depending on the supply design, the
supply may actually have slightly lower efficiency at the lower load
factor, but that's a trade off we can live with). Also consider what
happens if the load was near the capacity of a single supply, and spiked
over the capacity. If we were using the second supply as a "backup" to
only be switched in if the primary failed, how would that be handled?
--Rich
Matthew Sackman wrote:
>
> On Fri, Apr 27, 2001 at 12:05:11PM -0500, Dimitri Maziuk wrote:
> > On Thu, Apr 26, 2001 at 05:32:31PM -0700, Alvin Oga wrote:
> > ...
> > > - even if you had 2 power supplies...
> > > - most motherboards only has one atx power connector
> >
> > True. And if you went for redundant PS's and a mobo that
> > supports them, the cost would go way up.
> >
> > > - are the two power supplies properly doing load sharing...
> >
> > Usually not. I imagine that's too hard and not worth the trouble
> > anyway: what you usually want is redundancy, not load sharing.
> > (I mean, if one PS dies, it will overload and kill the other one
> > pretty fast. Not a good idea. And if each PS can handle the load
> > alone, there's little point in sharing the load.)
>
> Every production server that I've seen that has 2 PSUs has both
> continuously running. At hopefully < 50% capacity. There is no
> switch-over - if one goes then the other has to cope with both. Of
> course, the irony is that as they are both routed to the same power
> inlet, if the fuse in the plug goes then you're buggered anyway! :-)
>
> Matthew
>
> --
>
> Matthew Sackman
> Nottingham,
> ENGLAND
>
--
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Rich Puhek
ETN Systems Inc.
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