RE: ups <-> psu comms

In the past I did the maths for the sort of power down time that would suit my budget and availability to get to a site and fix a problem. Basically there was nothing reasonable to cover both bases. At the time I ended up putting UPS's in series and hoping that worked. (Which is why my gear is in a colo facility now).

I picked APC UPS's and they had a USB port that had a driver for Linux. Might not be what you are after but APC seem linux friendly.

I made a comment on luv-main recently that I was quite impressed by the APC UPS's I'd used in the past, but then someone said the newer ones had changed protocols and were no longer compatible with any known Linux driver. I don't know if the situation has changed since then. James