Date: Wed, 11 Aug 2010 16:01:47 -0700 From: "David Brodbeck" <gull@gull.us> To: "Ryan Coleman" <ryan.coleman@cwis.biz> Cc: freebsd-questions@freebsd.org Subject: Re: UPS question Message-ID: <cc009d380d95eaa9fee8328a6bbfe4fe.squirrel@www.gull.us> In-Reply-To: <3AB9F23A-B56C-4176-83C9-F248161066B9@cwis.biz> References: <E1B44814-1433-4FBE-902B-BCC1944FBFCD@cwis.biz> <3135A83C-6FD9-4C3B-958F-11EE85221061@mac.com> <5304A319-0406-4510-B6B2-8FD609239FF9@cwis.biz> <43a2b1b16a03a5c58dfb7beaadd0c535.squirrel@www.gull.us> <3AB9F23A-B56C-4176-83C9-F248161066B9@cwis.biz>
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On Wed, August 11, 2010 1:18 pm, Ryan Coleman wrote: > On Aug 11, 2010, at 3:06 PM, David Brodbeck wrote: > >> On Wed, August 11, 2010 12:25 pm, Ryan Coleman wrote: >>> He thinks that at 500W needed it would give me about 12 minutes on a >>> 1400VA. My consideration is, then, give the server 2 minutes on >>> battery. >>> If full power has not been returned, shut down the server but leave the >>> modem (w/ wireless) and switch running with power for up to 6 hours. >> >> A bit of advice: If this is an unattended system, give some thought to >> how >> you will boot the server back up if the outage is longer than two >> minutes >> but shorter than six hours. Most UPS installations have *some* kind of >> race condition issue if power comes back after the servers have begun a >> shutdown, but in your case it's an unusually long window. > > Meaning that my 2-minute window is unusually long? If the UPS can support > the system for 12 minutes, I say give it 20% of the life of the support > because our power outages here are usually spikes that kill my current web > server (but amazingly *not* my file server). In fact, one of those power > fluxes occurred last night. I love storms for the light shows, but hate > them for the toll they take on my servers. Nope, 2 minutes is fine, maybe even short depending on how long your system takes to shut down. What I'm asking about is this scenario: 1. Power goes out. 2. Server shuts itself down after 2 minutes. 3. Power comes back on before the UPS batteries are exhausted. The server never sees a power cycle, so it doesn't boot itself back up until someone physically goes and pushes the button.
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