The IBM Power Systems / Servers are based on Reduced Instruction Set Computer (RISC) technology. IBM have different models for very basic usage to scalable enterprise grade servers. IBM also provide small Linux servers, typically single purpose. Refer to the IBM Blog below for a more in-depth understanding on the different models of the Power hardware.
A Hardware Management Console (HMC) is used to manage power server(s) and is required depending on the model of hardware purchased. The HMC is typically a desktop style unit, or a 1U rack server. There is a “virtual HMC” which is called PowerVM Novalink. As of this writing PowerVM Novalink can ONLY be installed on Power8 processor-based servers and above. Other management solutions are PowerVC and some other OpenStack solutions. For more information on the HMC, refer to the HMC category on this website.
The IBM power systems are created to be virtualized from the ground up, and the majority of the time there are multiple operating systems running on a single power server. To achieve running multiple operating systems on a single server, virtualization is highly integrated. In fact, IBM use a product called “PowerVM VIOS” to virtualize the hardware and provide it to the client logical partitions (LPARs). Each LPAR will have a running Operating System on it, whether that be VIOS, AIX or Linux. VIOS and AIX are both proprietary software from IBM. I recommend visiting the HMC category to learn more about the Hardware Management Console (HMC).