“…There are simulators specifically for cloud research, for example CloudSim [21], but many researchers used their own simulation environments. Relatively few researchers tested their algorithms in a real environment [31,51,57,66,70,74,101,103,105] or using a combination of real hardware and simulation [85,93,95,104,109]. It has to be added though that in most of these cases, the "real" environment used for evaluation was rather small (e.g., just a handful of PMs and VMs).…”