UPS question

Ryan Coleman ryan.coleman at
Wed Aug 11 23:54:23 UTC 2010

On Aug 11, 2010, at 6:01 PM, David Brodbeck wrote:

> 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.

Good points. I just want to make sure it has a safe shutdown (the usual reason for a UPS) but it will be set with a BIOS turn on time if it is not on. This is for a mirrored archive that updates overnight. If it is in the middle of the process it will kill and shut off.

Most power outages in my area are 1) during the hottest days of the summer - like today and 2) last less than 60 seconds. It's biggest draw is to give it a steady stream of power.


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