Bare-metal, virtual machines and containers in OpenStack

Cloud computing is an on-demand access model for computing resources most notably embodied by the OpenStack project. As of release Liberty, OpenStack supports provisioning Bare-metal, Virtual machine (VM) and container based hosts. These different hosts incur different overheads. Consequently, the main goal of this paper is to empirically quantify that overhead through a series of experiments. The following drivers are leveraged in this process: Ironic for Bare-metal or Metal as a Service (MaaS), nova-compute for VM-based hosts, and nova-docker for Docker based containers. We make use of a private-cloud in order to compare the different options. This cloud is then used to compare the different hosts in terms of performance (CPU, networking, disk I/O and RAM) by using various open-source benchmarking tools. We also measure boot-up times. The output of these benchmarks is collected and results are compared. In this paper we discuss our learnings as well as the different configurations and fine-tuning that we implemented. As a result, we provide a set of recommendations based on the advantages and disadvantages of each host in present and future cloud deployments.