For software, a bare-metal virtual machine hypervisor such as VMware’s vSphere ESXi or Mirantis OpenStack, with a management console such as VMware’s vCenter Server or HP’s Horizon Management. For network architecture, possibly a Software Defined Network (SDN) managed by a controller such as VMware NSX or Cisco’s ACI. But does it scale? Does the data center operator have a realistic sense of how much load this rack can handle when fully populated, with tens or hundreds of thousands of virtual machines? Does the owner have confidence enough in the capacity in order to effectively price its services, and back them with money-back SLAs? This whitepaper gives you answers about how to scale test your clouds instead of taking an educated guess.