-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of alex@pilosoft.com Sent: Friday, April 22, 2005 8:07 PM To: Mike Sawicki Cc: nanog@merit.edu Subject: Re: Dual rackmountable power supply?

On Fri, 22 Apr 2005, Mike Sawicki wrote:

...

Do any of you know if there are companies who manufacture 1/2U rackmountable PDU's that take AC from redundant sources? I have equipment at a colo that seems to have issues with one of the two circuits in my cabinets about once a month. Since it would be a real pain in the neck for me to retrofit every server with dual-ps, I was thinking this could be a possible middle-of-the-road solution. Thanks. This is called a "Static Transfer Switch". (Sometimes "automatic transfer switch", particularly for smaller units). Number of companies make small ones:

http://www.baytechdcd.com/cgi-private/showprod?prod=F5-RPC http://www.baytechdcd.com/cgi-private/showprod?prod=ATS12-30 http://twinsource.net/ http://www.apc.com/products/family/index.cfm?id=14 http://www.mgeups.com/products/pdt230/sts/psts/stsa.htm

I don't think you can place these on the pointy side of conditioned power. They require utility, IIRC, which means you also need to add in some UPS for the front side to make it work right since utility will tend to take 'switch hits' during peak as the utility moves load around. WRT to the flapping power circuit, blind guess, ask your colo provider to measure the load at your breaker and if it's fine then swap the strip and chords (twistlock or not) back to the first JB. -M< -- Martin Hannigan (c) 617-388-2663 VeriSign, Inc. (w) 703-948-7018 Network Engineer IV Operations & Infrastructure hannigan@verisign.com