When a disaster happens, you may lose a part or all of your data. In general, a disaster is defined as a temporal or permanent loss of the whole service with no guarantees that it will become available again. Such disasters are floods, earthquakes, or fires, just to name a few. Disasters tend to occur in a single region (the probability of disasters occurring in separate regions simultaneously is very small), so in general you need two different data centers to implement disaster recovery (DR).
Remember, using two different data centers may not be enough if they are close to each other—you have to select two that can satisfy your requirements, but at the same time are as far from each other as possible.
When it comes to ...
