it depends however whether you want to test the code or the infrastructure
my preproduction uses a three machines setup so it can catch clustering problems, but the code itself can run just as well on a single machine interacting with a local single instance db, and devs run it like that.
my preproduction uses a three machines setup so it can catch clustering problems, but the code itself can run just as well on a single machine interacting with a local single instance db, and devs run it like that.