I work for a data center as I have seen many others do as well.
Here we have 6 Hitec generators to power just our second floor (approx 50,000 square feet). Only 3 are needed. These generators are normally powered buy grid power that comes into the facility from the north and the south. Should there be any bump in power we have stores of batteries that take the load for 5-50 seconds until the generators switch to desiel. Temperature and power are monitored 24/7 by the NOC.
The main point that needs to be made here is that powerlosses of any kind are bad for business so don't have them. This happens from constant monitoring, proper maintance for your redundant power, and foresight to plan for the unplanned ( if that makes any sense). It seems to me that the failure in Dallas was caused by failure to keep maintance up or poor planning for eventual outcomes.