UPS question

[Ryan Coleman]

On Aug 12, 2010, at 12:52 PM, Al Plant wrote:

> 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.
>> ##########
> 
> I have had these power dips and surges here in Hawaii. I have installed  UPS power from two stationary batters that will run the servers for 12 hours. We have experienced extensive outages in the past and this was our only solution. Surges are almost impossible to stop. I have them jump cross a surge protector. I have recently  had several UPS Desktop backups fail from a surge and then a drop below 70 v. This caused the UPS to have the charging diodes blow. It was cheaper to replace the UPS 's than to repair them.
> 
> #3. The motherboard bios can be set to stop a server from self booting from a power outage.
> 


Yes. The downside comes from when the BIOS is told to turn on the server at, say, 10pm and the power is still out... it starts the process and runs out of battery mid-way through the boot before it gets the chance to load the UPS controller.

--
Ryan