UPS expectations

[Kyle Waters]

Due to nearby construction we have had a couple of power outages 
recently and I've been asked to evaluate our batter backup system(we are 
not able to put generators in place currently). I have a few questions 
for other regarding there batter back up systems.

What is a reasonable expectation for a rack mountable UPS to continue to 
supply power during a power outage?

How much equipment do you generally put on one 
UPS(servers,switches,routers)?

Any software you have found that works well with CentOS to shut down the 
servers at the appropriate time?

How frequently should UPS be tested? How should they be tested?

How frequently do you replace batteries/UPS' due to failure?

Kyle