Help with UPS

[HomerJ]

Hi all

 

The time has come for me to purchase a UPS for my server. 

 

I have never bought one of these before. I have just checked the server and everything is running attached to a 1200W PC power supply. 

 

So far I've found this: CyberPower Systems Value 2200ELCD Value SoHo Line Interactive UPS https://amzn.asia/d/gMa0pFc

 

From what I can understand, this should give my server a little over a minute to power down before the battery runs out, right? 

 

I just want to make sure that I understand. Thanks!

[JonathanM]

3 hours ago, HomerJ said:

From what I can understand, this should give my server a little over a minute to power down before the battery runs out, right? 

It's not that simple. To figure out the correct (for you) size for a UPS you need more information. Critical parts of the whole picture are...

1. Idle power draw in watts (not critical to measure accurately, more just good info)

2. Max continuous draw with all drives spinning and actively being accessed, parity check with all typical VM's and containers running is a good time to measure.

3. Instantaneous surge when transitioning from idle with no drives spinning to a parity check. (Hard to measure without really special equipment, but still important to estimate)

4. Unattended shutdown time. How long does the machine take from fully active to powered off if you stop the array then power down, assuming everything is running like it normally does, no fair preemptively stopping VM's or containers.

5. Typical outage length. Do you have multiple 5 minute outages? Or just 5 second or less blinks? If the power is out for at the 1 minute mark, how likely is it to still be out hours later?

 

For power draw measurements, you really need a meter, something relatively cheap and simple should work fine. I can't tell what part of the world you are in from that amazon link, but here is something like what you need. link

 

The max capacity of your PC power supply has little if anything to do with actual draw, you really must measure how much it pulls from the wall to figure out what you need.

 

Keep in mind that if the UPS uses SLA batteries (almost all do), they really dislike being discharged below 50%, it's not good for their lifespan, so after you get your real load numbers you should try to stay in the first 50% of the runtime chart for the full shutdown time.

 

The UPS you linked may be overkill, or just right, or too small. No way to tell without finding actual usage figures.

[HomerJ]

That is a fantastic reply!!!! I really appreciate the time and thought you put into it! I have a power meter somewhere, I'll find it over the weekend and start getting some figures. 

[JacekR]

The watt meter that Jonathan linked say's it's unavailable when I clicked it, so here is an alternative that costs $12.

 

The size of the PSU you have is irrelevant to the UPS you need.  Actual wattage draw is what is important, as most PCs and servers are designed with larger PSU's to get into the efficiency band under load.  Which on most PSU's is between 40% - 60% load.

 

As an example I have a APC UPS 1500VA / 900W for my unraid server. At idle (45w) it gives me a 75 minute runtime at full load (425w) it gives me 11 minutes 49 seconds of runtime.

 

btw:  I noticed you can not trust the 'estimated runtime' as listed on unraid if your idle draw is lower then the UPS minimum draw.  The UPS I use has a minimum draw of 90w when on battery, so anything under 90w of draw has the same runtime of 75 minutes.  If you scroll down on the specs page for the UPS I have you'll see field you can enter your Wattage draw to see what the runtime will be, and the min-max is 90w - 900w.  Most UPS's devices you look at, the manufacturer will have specs you can check for how long the runtime will be based on wattage use.

[HomerJ]

Thanks for your reply! 

 

I had one of those smart meter plugs which I've just found and attached to my server. I'll now do some testing. 

[JonathanM]

6 hours ago, JacekR said:

The watt meter that Jonathan linked say's it's unavailable when I clicked it, so here is an alternative that costs $12.

That is a USA 110v version, if you looked at the UPS he referenced, it is NOT a 110v. Power meters must match the regional requirements.

 

What I linked to IS available if you live in Australia, to see that you must select an AUS delivery address.

[JacekR]

2 hours ago, JonathanM said:

That is a USA 110v version, if you looked at the UPS he referenced, it is NOT a 110v. Power meters must match the regional requirements.

That is a good point, i didn't realize the voltage wasn't 120v.