OS (VM)

• A virtual machine is a virtual representation, or emulation, of a physical computer.
• Virtualization makes it possible to create multiple virtual machines, each with their own operating system (OS) and applications, on a single physical machine.
• A lightweight software layer called a hypervisor coordinates between the virtual machines and the underlying physical hardware.
• The hypervisor allocates physical computing resources—such as processors, memory, and storage—to each virtual machine.
• The hypervisor keeps each virtual machine separate from others so they don’t interfere with each other.
• Virtual machines can go by many names, including virtual server, virtual server instance (VSI) and virtual private server (VPS).
• When a hypervisor is used on a physical computer or server, it allows the physical computer to separate its operating system and applications from its hardware.
• Type 1 hypervisors run directly on the physical hardware (usually a server), taking the place of the OS.
• Typically, you use a separate software product to create and manipulate virtual machines on the hypervisor.
• Type 2 hypervisors run as an application within a host OS and usually target single-user desktop or notebook platforms.
• With a Type 2 hypervisor, you manually create a virtual machine and then install a guest OS in it.
• Virtual machines offer several advantages, including improved resource utilization and ROI, scale, portability, flexibility, and security.
• Cloud computing has been a major use case for virtual machines, enabling dozens of different types of applications and workloads to run and scale successfully.
• Virtual machines are a great way to support enterprise developers, who can configure VM templates with the settings for their software development and testing processes.
• Virtual machines are useful for malware researchers that frequently need fresh machines on which to test malicious programs.
• Using a virtual machine for browsing enables you to visit sites without worrying about infection.
• A user could set up a temporary virtual desktop located on the server for browsing securely.
• An admin could provide a temporary virtual desktop located on the server for browsing securely.
• Resource utilization and improved ROI: Because multiple VMs run on a single physical computer, customers don’t have to buy a new server every time they want to run another OS, and they can get more return from each piece of hardware they already own.
• Scale: With cloud computing, it’s easy to deploy multiple copies of the same virtual machine to better serve increases in load.
• Portability: VMs can be relocated as needed among the physical computers in a network.
• VMs can even move between on-premises and cloud environments, making them useful for hybrid cloud scenarios in which you share computing resources between your data center and a cloud service provider.
• Flexibility: Creating a VM is faster and easier than installing an OS on a physical server because you can clone a VM with the OS already installed.
• Security: VMs improve security in several ways when compared to operating systems running directly on hardware.
• A VM is a file that can be scanned for malicious software by an external program.
• You can create an entire snapshot of the VM at any point in time and then restore it to that state if it becomes infected with malware, effectively taking the VM back in time.
• • Resource utilization and improved ROI: Because multiple VMs run on a single physical computer, customers don’t have to buy a new server every time they want to run another OS, and they can get more return from each piece of hardware they already own.(Advantages of VM)
• With cloud computing, it’s easy to deploy multiple copies of the same virtual machine to better serve increases in load.
• VMs can be relocated as needed among the physical computers in a network, making it possible to allocate workloads to servers that have spare computing power.
• VMs can even move between on-premises and cloud environments, making them useful for hybrid cloud scenarios in which you share computing resources between your data center and a cloud service provider.
• Creating a VM is faster and easier than installing an OS on a physical server because you can clone a VM with the OS already installed, allowing developers and software testers to create new environments on demand to handle new tasks as they arise.
• VMs improve security in several ways when compared to operating systems running directly on hardware.
• You can create an entire snapshot of the VM at any point in time and then restore it to that state if it becomes infected with malware, effectively taking the VM back in time.