Redundant PSU's

[Slartibartfast]

uOpt's thread (http://www.jonnyguru.com/forums/showthread.php?t=289) and Spectre's suggestion has me a tad curious about redundant power supplies. My understanding is that they're technicaly two psu's in one package. In the event of one psu failing, the second takes over. Also, does anybody know of a good place to buy 'em? I'd like to look at a few models and their specs. I know you can find some at servercase.com, but their descriptions are pretty shitty (for example, "8 big plus 2 small connectors").

edit: servercase also carries ATX Zippy PSU's: http://www.servercase.com/miva/miva?/Merchant2/merchant.mv+Screen=CTGY&Store_Code=SC&Category_Code=4U_Server

They're listed as Emacs, not Zippy. They have a pretty good selection, I've seen 400w - 850w models. There's no organization so you have to dig a bit.

[Oklahoma Wolf]

www.powersupplypartner.com (http://www.powersupplypartner.com) carries several different names IIRC, including Zippy and Etasis.

[Slartibartfast]

Aye, they've got a fair amount of selection...

[Spectre]

Honestly most time I see them they come in preinstalled in the chasis....we purchase them as an all in one solution and don't really mix and match to make DYI rackmount's. When we need a replacement we call the vendor...but you can find them at servercase, chumbo, costcentral I think, myaopen used to carry them. A lot of places on the web though will list the PSU by the case makers name...ie it will say Tyan or Chenbro when it really is a Zippy.

[uOpt]

No, they are usually three, not two PSUs.

In the Supermicro model you have three slots for modules of 350 watts each.

Normally two are running, giving you 700 watts of power. One dies, the third takes over, the machine cries for an operator to exchange the broken one. Once inserted, the new one is the spare.

%%

Having said that, the reliability per module is certainly a lot less than that of a single PSU. The modules, packing 350 watts each, are cramped in very tiny space, with high-pressure fans. So although they improve your uptime they also increase your failure rate.

[Oklahoma Wolf]

No, they are usually three, not two PSUs.

1+1 is fairly common too.

[Spectre]

Having said that, the reliability per module is certainly a lot less than that of a single PSU. The modules, packing 350 watts each, are cramped in very tiny space, with high-pressure fans. So although they improve your uptime they also increase your failure rate.

I don't have concrete numbers but we don't see that high a failure rate on our redundant PSU's....maybe we are just getting better units or we have a cooler running set of racks...but we don't have mass failures....we replace drives a lot though.