As mentioned earlier, the ideal replica set would consist of a minimum of three computers. To give an example of a bad design, consider three old computers, each with an old, outdated OS, sitting on a shelf next to each other in the same room. As you can deduce from this simple example, the number of computers in a replica set is not the only consideration. What we need to look at now are positive suggestions on what would comprise a smoothly operating replica set.
The elements of a proper replica set design are listed here:
- Identical host environments: The environment could be a physical server, or it could be a virtualized host instance. The elements of the host environment would include an OS upon which a mongod instance is running and a suitable filesystem. What is important in this context is that the environment does not have to be identical for all replica set hosts. However, the more closely the environment of each member of the replica set resembles...