By this point, you are most likely convinced that implementing your database using a replica set makes good sense. In order to justify the purchase of the extra resources required to support a replica set, however, you need to determine the following:
- What is the cost of downtime?: A related question to ask is how much money is lost if the database goes down? Unfortunately, you cannot give a blanket answer to this question. You need to do further research to find out how much your business makes, on average, every second. This might seem like a ridiculous figure to have to calculate, but consider this: downtime is usually (hopefully!) measured in seconds. So, if your server goes down for 30 seconds, you need to know, on average, how much money is lost.
- How important is uninterrupted service?: An often overlooked hidden cost is what is informally described as the customer irritation factor. When the database goes down or is unavailable for some reason...
