[Nut-upsuser] Can this be done with NUT? (ordered shutdown, revisited)

[Steffen Grunewald]

Good morning everyone,

we're currently in the process of redesigning our UPS signalling scheme,
and decided to have a closer look at NUT.

This is our setup:
- a (really) big UPS (Piller, with a web/SNMP interface)
- several computer rooms with equipment of different importance,
  managed by several people not sharing ssh keys etc., with an
  unknown number of machines
- IPMI signalling to forcibly kill, or wakeup individual machines

Our goal is to:
- provide a single point of information (ideally, a laptop that can
  continue running on its own battery)
- let clients decide whether "their" power supply can still be 
  considered trustworthy
- have different "low battery" conditions (charge levels) for groups 
  of computers, hoping that reduced load would give other, more
  essential services, a longer runtime
- NOT base shutdowns on timers (because changing loads will also change
  the discharging curve)

What I currently tried:
- I found a longish discussion on this list, dating back to six years
  ago: http://lists.alioth.debian.org/pipermail/nut-upsuser/2009-February/004772.html
  In particular, Marco's requirements look quite similar to ours, but
  there was apparently no solution (back then). I mayhave missed a later
  continuation though.
- Use multiple drivers, with override.battery.charge.low set to various
  levels - or "dummy-ups" repeaters with the same modification
- Let client groups upsmon-read one of those "virtual" UPSes

What I found:
- upsd obviously doesn't calculate LB itself (even if charge.low is set
  to 105.00 for testing purposes). Does this only happen on OB, or does
  upsd do no calculations at all?
  Apparently, ordered handling of multiple shutdown conditions cannot be
  done this way?

Is there still a way to provide, at a single central point, multiple 
UPS conditions that can be used by multiple upsmon client processes?
There is a simple reason why I don't want to do excessive upssched etc.
work on each individual client when a single bit of information should
suffice. There is no general way to reach a client from the UPS manager
machine (as in ssh, telnet, etc.), just the UPSD port.

Or should I look for something else (recommendations off-list)?

Thanks,
 Steffen

-- 
Steffen Grunewald, Cluster Administrator
Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
Am Mühlenberg 1
D-14476 Potsdam-Golm
Germany
~~~
Fon: +49-331-567 7274
Fax: +49-331-567 7298
Mail: steffen.grunewald(at)aei.mpg.de
~~~