[Nut-upsdev] Questions about failover architecture

[Greg Troxel]

Wow, that's quite the tale!

I take away from this:

  There is a real example of wanting to merge two information sources.

  It's very complicated.

  Anybody wishing to succeed in a very complicated situation needs to
  really pay attention, to twice as many things as they thought when
  they started.

  It's unclear how to generalize from this to a solution that will work
  for the next person.

but if someone wants to write soemthing that is an aggregating driver
(looks like a driver, talks to N driver), and do so in a way that
doesn't cause any significant pain for others that seems like a fine
thing for them to do.

I would suggest having some sort of config file that for each variable
says which driver to prefer, and some kind of timeout for not available
to flip to the backup.  I guess for starters, one could configure two
drivers in "fancier/less-reliable" and "old-school" slots, and prefer
fancier for all except shutdown and status.

I fear that the next layer is merging status from two where they don't
quite match.