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suggestions for a UPS

Message #1 - Posted 2011/11/21 - paris2venice

I want to buy an APC UPS but there is such a wide selection, I don't know where to begin. I need it for a 2006 (bought it in 2008) Xserve. Can anyone make a suggestion or send me to a site that evaluates UPS devices that would get me started? Thanks a bunch.

Message #2 - Posted 2011/11/21 - JF Mezei

paris2venice wrote:

I want to buy an APC UPS but there is such a wide selection, I don't know where to begin. I need it for a 2006 (bought it in 2008) Xserve. Can anyone make a suggestion or send me to a site that evaluates UPS devices that would get me started? Thanks a bunch.

If you use the Server Monitor application (IPMI protocol), you can see the power consumption of the unit. ( And it is fairly accurate within about 10 watts.

The 2009 Xserver with 1 CPU consumes about 180 watts. (Power, System Poard, Estimated Input Power)

I bought a use SUA1500RM2U unit recently from UPSFORLESS. They are refurbished units with new batteries.

http://www.upsforless.ca/

for the USA: http://www.upsforless.com/

The unit is very heavy. Remove battery when you get it, you can then install it on the rack and then slide the battery pack in.

Interestingly, the Server Monitor application now show UPS information as well in the Power Section

Message #3 - Posted 2011/11/22 - David Empson

JF Mezei wrote:

paris2venice wrote:

I want to buy an APC UPS but there is such a wide selection, I don't know where to begin. I need it for a 2006 (bought it in 2008) Xserve. Can anyone make a suggestion or send me to a site that evaluates UPS devices that would get me started? Thanks a bunch.

If you use the Server Monitor application (IPMI protocol), you can see the power consumption of the unit. ( And it is fairly accurate within about 10 watts.

The 2009 Xserver with 1 CPU consumes about 180 watts. (Power, System Poard, Estimated Input Power)

That would vary depending on CPU load (and anything else like power-hungry PCI Extreme cards). The maximum power draw could be more than double that in some situations, so you probably should monitor it for a while and note the average and peak power before selecting a UPS.

I bought a use SUA1500RM2U unit recently from UPSFORLESS. They are refurbished units with new batteries.

I can't find that model number on the APC site. Is it actually an "SUA1500RMI2U" (international, i.e. 230V) or is the APC US site just not admitting it exists because it is an older model?

Diverting the thread slightly...

I've recently bought an APC Smart-UPS SMT750I (entry level model in this series, "brick on the floor" rather than rackmountable), for my Mac Mini Server. Certainly has plenty of capacity to keep the Mac Mini running for well over half an hour (along with external hard drive and Drobo). The UPS uses about 20% load while the server is mostly idle (but with all hard drives running apart from the Drobo).

One catch I've noticed is that Mac OS X Server 10.6's UPS monitoring via USB doesn't quite work with this model, and based on some research this is likely to extend to all of APC's "SMT" or "SMX" models. APC has switched to a new communication protocol with this series, and they apparently haven't published it for anyone else to use (refer to http://apcupsd.org for some background). Apple's standard UPS driver seems to be affected by this as well.

The Mac can detect whether the UPS is running from mains or battery, but it doesn't report the battery level, claiming to be at 100% capacity all the time. This makes it impossible to use auto-shutdown modes based on remaining capacity of the UPS battery or estimated run time left. I've worked around it by instead using a "shut down after N minutes" configuration, but I had to use "sudo pmset -u haltafter 40" via Terminal to get 40 minutes, since System Preferences won't let me specify more than 15 minutes for that mode.

The SUA series is older than the SMT/SMX series, so it probably works fine with Mac OS X's standard USB driver, because it uses the old protocol.

There is an optional add-on card for the SMT/SMX models which gives serial and USB ports that implement the old protocol. I may get one of them if all else fails, but I'll complain at APC and Apple (via a bug report) first. Need to try it with Lion to see if it has a new driver.

Today was the first time I had to use the UPS in anger, since our power meter was being replaced. Power was out for 30 minutes and the battery got down to about 65% (as reported by the display on the UPS), so I think I'll be fine with a 40 minute forced shutdown, even if CPU load is somewhat higher than average.

Some general background on two of the series offered by APC:

- The "Back-UPS" models are entry level and intended for home use. They generate a stepped approximation of a sine wave and are not suitable for anything which has a power supply which might be sensitive to waveform distortions (e.g. active power factor correction). This is more likely with workstation and server power supplies, so these wouldn't be a good choice for an Xserve.

- The "Smart-UPS" series output a proper sine wave. At the same rating there may be several variants, which are a combination of older vs newer models, and ones with additional options, e.g. SMX vs SMT has the option of adding an external battery (and thereby getting extended run time). RM in the model name means it it rackmountable, 1U/2U refers to the number of rack unit positions it occupies.

Have a look at the graphs on www.apc.com for the models you are considering to get an idea of how much run time to expect for a given load.

http://www.upsforless.ca/

for the USA: http://www.upsforless.com/

The unit is very heavy. Remove battery when you get it, you can then install it on the rack and then slide the battery pack in.

Interestingly, the Server Monitor application now show UPS information as well in the Power Section

David Empson
dempson@actrix.gen.nz

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