Which of the following is not included in the physical architecture of a server?

A server's architecture is typically described in layers. The foundational layer is the physical hardware (CPU, memory, storage). The next layer is system software, which includes the Operating System (OS) or a Virtual Machine Monitor (VMM/hypervisor) that directly manages the hardware. Applications are user-level programs that run on top of the OS or within a VM. While the server's purpose is to run applications, the applications themselves are not considered part of the server's core system or physical architecture; they are the workload the architecture supports.

B. VMmonitor: A VMM (hypervisor) is a core system software component in a virtualized server architecture, directly managing the hardware.
C. OS: The Operating System is the fundamental system software that manages all hardware resources and provides a platform for applications.
D. Hardware: This is the physical foundation of the server and is the definition of its physical architecture.

1. Patterson, D. A., & Hennessy, J. L. (2017). Computer Organization and Design RISC-V Edition: The Hardware Software Interface. Morgan Kaufmann. Chapter 1, Section 1.4, "Under the Covers," illustrates the layered system architecture from applications down to hardware.

2. Huawei. (2020). Huawei Server Operating System EulerOS V2.0 Technical White Paper. Section 2.1, "Architecture," shows the OS as the layer between hardware and applications, defining it as a core part of the server's software architecture.