The term bare metal is a reference to a computer’s hard disk – the medium on which the operating system (OS) is installed. A bare-metal environment is a specific kind of virtualization environment built with bare-metal hypervisors that do not rely on a host OS in order to function. In a bare-metal environment, the virtualization hypervisor is installed and executed directly on the hard drive (bare metal) and can create virtual machines (VMs) from there, just as in a virtualized environment with a host OS.
Bare metal plays a variety of roles in the modern data center. Legacy hardware, core business apps like ERP and specific apps required by an organization often drive the requirement for bare-metal workloads in the data center. Bare-metal servers are a good fit for high performance computing (HPC) applications, because they are free from normal virtualization overhead. Bare-metal cloud servers based on OpenStack have demonstrated superior performance during industry testing. And some applications, such as in-memory databases or heavy-duty analytics products, can consume all of the available CPU resources of a host, making a bare-metal server a better option.
Bare-metal provisioning takes place when an operating system (OS) or bare-metal hypervisor is installed directly on a computer’s hard disk. This can be done manually via CD or hypervisor DVD, or automated with special software. Bare-metal provisioning plays an important role in the modern software-defined infrastructure (SDI), where organizations use automation to operate at peak efficiency. Tools such as SUSE Manager can provide unattended bare-metal provisioning and allow any bare-metal system in the network to be easily inspected, migrated, and provisioned by administrators. OpenStack also includes bare-metal provisioning services via OpenStack Ironic, which lets users provision bare-metal machines instead of traditional VMs using the same basic concepts and tools.