[Nut-upsuser] Why are LAN ports not standard on UPSs these days?

Philip Rhoades phil at pricom.com.au
Sun Jun 25 18:18:52 UTC 2017


On 2017-06-26 03:43, Charles Lepple wrote:
> On Jun 25, 2017, at 8:53 AM, Philip Rhoades wrote:
>> I don't understand why most of the UPS offerings available do not come 
>> standard with a LAN port? Why is this?
> As others have mentioned, it probably comes down to cost for a port
> that is not frequently used.
> Something to consider is that there are add-on cards with LAN ports
> for mid- to upper-tier UPSes. Some cards also have environmental
> monitoring options as well.
> On the other hand, these cards do not seem to be high-volume items,
> and the prices reflect that. If you don't need fancy temperature
> sensing, a Raspberry Pi or other single-board computer is IMHO a
> better way to spend that money (and it will probably turn out to be
> more versatile).
> One thing about the NUT master/slave architecture is that it forces
> you to consider the shutdown order. The NUT master is responsible for
> commanding the UPS to turn off the power, so at that point, the master
> system should not be depending on any other systems for their
> services. A LAN card with SNMP doesn't really enforce this hierarchy,
> but then again, there are probably some high-availability cases where
> SNMP makes more sense.
>> Do people have suggestions about my options?  I have two main machines 
>> - say 250-400W total and a few small devices inc a Billion router and 
>> some USB devices.
> Be sure to factor your network infrastructure into that power estimate
> - you will want the network links between NUT master and slave systems
> to be on battery power as well, or else the master will resort to
> guessing  the status of the slaves.
>> It would be nice to have at say 5-10 minutes battery backup before 
>> sending shutdown messages to the Linux machines.
> When you take the 5-10 minutes of runtime and turn that into a
> requirement for battery capacity, it is worth considering what amount
> of reserve power you would want in case you need to briefly power up a
> machine during an extended outage. I would also recommend buying an
> UPS that allows you to adjust its low battery threshold in terms of
> estimated remaining runtime (and not just percentage of full charge),
> as this should prevent surprises later as the battery ages. (The UPS
> should keep track of changes in runtime for a given load as part of
> its periodic calibration, automatic or manual.) The NUT variable for
> this limit is "battery.runtime.low" (expressed in seconds).
> This brings me to the Device Dump List:
> http://new.networkupstools.org/ddl/ (or
> http://networkupstools.org/ddl/ if the first link is not working).
> Because suggestions are an inherently subjective topic, we have some
> user-provided data dumps of the readable and read/write values
> provided by many UPS vendors. We also try to flag values that are
> problematic in some way (wrong scale factor, doesn't ever update,
> etc). Ideally, we would fix this in the driver, but in some cases,
> that can be difficult to fix without breaking something else.
> A more subtle aspect of the DDL is that you can see how the underlying
> firmware changes over time for the same marketing model name. For
> instance, there are two versions of the Tripp-Lite OMNIVS1000 with
> different internals, and as such, slightly different feature sets.
> Feel free to ask about any of these results - the underlying DDL
> repository has some links back to the source of these reports. You can
> often find discussions for other devices in the nut-upsuser archives.

Wow!  Thanks for all of that!  I will start looking at it all . .


Philip Rhoades

PO Box 896
Cowra  NSW  2794
E-mail:  phil at pricom.com.au

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