Virtualisation & Hypervisor Flashcards
What is the main goal of an operating system in managing resources for processes?
The main job of an operating system is to present an idealized computer to every process, offering it every possible service while maximizing the use of available resources, even in the presence of competing processes with different requirements.
What are the two prominent aspects of virtualization in many operating systems?
The two prominent aspects of virtualization in many operating systems are virtual memory and time-sharing. Virtual memory allows any process to use almost any address at any time, while time-sharing enables the concurrent execution of multiple processes on physical processors.
What is the principle employed by operating systems in virtualizing resources?
Operating systems follow a principle similar to Harrods’ motto “Omnia Omnibus Ubique” (all things for all people, everywhere). They maintain the potential of many resources and organize the actual resources based on demand. Resources are allocated dynamically when needed.
Can you provide an example of resource virtualization in operating systems?
An example is memory virtualization, where a process can use any address it wants, but the actual memory allocation is done when the process accesses that address. Another example is printing, where output can be printed at any time, and the system queues the output until a free printer is available for allocation.
How can an operating system be described in terms of providing a virtual machine for application processes?
An operating system acts as a software layer that provides a virtual machine for application processes to run on. Each application process can operate as if it is alone on a machine with its own set of devices and memory. The operating system serves as the interface to the physical hardware.
What is the purpose of a hypervisor in the context of operating systems?
A hypervisor extends the concept of an operating system by adding another layer of software between the operating system and the hardware. This allows multiple operating systems to run concurrently on a single machine, similar to how multiple applications can run on a single operating system.
What are the advantages of using a hypervisor for running multiple operating systems on a single machine?
The advantages of using a hypervisor include the ability to support various software on one physical computer, easy portability of software when upgrading hardware, minimal reconfiguration requirements, cost savings on maintenance and electricity by consolidating applications onto one powerful machine, and the ability to run multiple applications concurrently using resources intermittently.
How are hypervisors classified into different types?
Hypervisors are classified into two types: Type 1 and Type 2. Type 1 hypervisors are adjacent to the hardware and provide a virtual machine environment for operating systems to run. Type 2 hypervisors run under a host operating system and operate as an application program, providing a virtual machine environment with some performance penalties and less flexibility in resource allocation.
What is the main difference between Type 1 and Type 2 hypervisors in terms of their location and hardware interaction?
The main difference is that Type 1 hypervisors are adjacent to the hardware and separate the physical computer from other software, while Type 2 hypervisors run under a host operating system. Type 1 hypervisors require hardware support and offer better performance by allowing applications to run directly on the hardware, while Type 2 hypervisors rely more on software emulation, resulting in performance penalties.
