Computer systems have become a critical part of most businesses including dentistry. If the computer fails what do you do?
Some people are so afraid of a computer crash they use the possibility as an excuse not to use digital technology at all. Based on that kind of thinking you should use candles instead of electric lights because the power might go out.
Of course sometimes the power does go out. What do you do? You deal with it. In the modern world we rely on technology like the power grid that can and does fail on occasion. When it fails we cannot do everything we can do with the power on. We cannot treat patients we will need to re-schedule. It is an annoyance it is not a catastrophe.
In dentistry we have a number of mission critical systems. If they fail we cannot do dentistry. This includes the air compressor, the central vac and even the curing light. Most dentists have an emergency plan to back up a failure in a mission critical system. You may have a small emergency compressor or have an arrangement with your supplier to bring and install a loaner within a specified time.
You need to have exactly the same type of arrangement with your IT supplier. That is an emergency plan to get the office up and running within a few hours or a day at most in the unlikely event of a major computer system failure.
There are several ways to do this with redundant drives, RAID arrays and cloud back up. The exact mechanism is not as important as the plan. If your IT provider does not or cannot guarantee to have a failed system up and running in less than a day, fire them.