Advantages: 1) Effective resource usage 2) Manageability 3) Security
Concepts:
Hypervisor is the manager of the Xen enviornment. It controls and provides acess to resource like CPU, memory, storage. It's started by the bootloader and acts as traffic controller for all virtualized OS. It control migration, starting, stopping, and puasing the virtualized OS. There are 2 types of virtualizations.
Paravirtualization: It's the native mode of Xen. Performance is the main advantage incurs no more than 5 % performnace impact v.s bare hardware
Full Virtualization: Xen provides a complete machine simulation to run OS which does not include Xen support. The extra operations make the OS beliving that it runs on bare hardware add overhead. Therefore, the performance impact is greated than paravirtualization.
Xen Domains: Xen virtual hosts. The first domain loaded is called Domain-0. Domian-0 is booted immediately after the hypervisor starts and provides the user interface at the console. It's used to install and manage other domain. Any virtual machine other than Domain-0 is called Domain-U. Dom-U has no visibility of the hypervisor or the physical hardware
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