No large data centre that worth the name didn't prepare for that. In case of massive power faiture, the entire chain from grocery stores up will be shut down to prevent transaction record loss
The main difficulty with india has to do with grass root tax evasion and bribery
In Bharat,
Low level bribery currency--paper money
Mid-level bribery currency--high denomination paper money(which modi wants to ban) and precious metal
Top level bribery medium--Swiss/caribbeans bank accounts through money laundry