The ability to run multiple machines with separate Operating system and Application on a single machine is Virtualisation. In other words the technology with which we can transform hardware into software is Virtualisation. Virtualisation uses either Hosted Architecture or Bare-Metal hypervisor Architecture.
HOST BASED VIRTUALISATION
It requires an Operating System to be installed on a computer. For example a computer which is running Windows 7/xp or any linux Operating system, VMWare server or workstation Virtualisation layer is installed on it. This is called host based Virtualisation. Once VM ware server/workstations version is installed, virtual machines can be created and deployed. This virutal machines will have their own Operating Systems and set of Applications. Though this is good solution in testing environment and production environment to certain extent but this might not be an idle solution for production environment. There are few drawbackups e.g. rebooting hosting OS means all virtual machines will be rebooted too and many more.
VIRTUALISATION USING A BARE-METAL HYPERVISOR
A Bare-metal hypervisor system does not require an operating system. The Hypervisor itself is an Operating System. It installs the virutalisation layer directly on a clean x86-based system. Because a bare-metal hypervisor architecture has direct access to the hardware resources, rather than going through the Operating System which make it more efficient than hosted architecture. This delivers greater scalability, robustness and performance. A hypervisor is the primary component of virtualisation that enables basic computer system partitioning i.e. simple partitioning of CPU, memory and I/O. VMware ESX/ESXi employs a bare-metal hypervisor architecture on certified hardware for datacenter-class performance.
WHAT IS A VIRTUAL MACHINE
From a user's perspective, a virtual machine is a software platform that like a physical computer runs an operating system and applications.
From Hypervisor's perspective, a virtual machine is a discrete set of files. The main files are as below;
- Configuration file
-Virtual disk file
- NVRAM settings file
-Log file
WHY VIRTUALISATION
Virtual machines have many advantages over physical machines.
Virtual machines are easy to move and copy across different hosts.
HOST BASED VIRTUALISATION
It requires an Operating System to be installed on a computer. For example a computer which is running Windows 7/xp or any linux Operating system, VMWare server or workstation Virtualisation layer is installed on it. This is called host based Virtualisation. Once VM ware server/workstations version is installed, virtual machines can be created and deployed. This virutal machines will have their own Operating Systems and set of Applications. Though this is good solution in testing environment and production environment to certain extent but this might not be an idle solution for production environment. There are few drawbackups e.g. rebooting hosting OS means all virtual machines will be rebooted too and many more.
VIRTUALISATION USING A BARE-METAL HYPERVISOR
A Bare-metal hypervisor system does not require an operating system. The Hypervisor itself is an Operating System. It installs the virutalisation layer directly on a clean x86-based system. Because a bare-metal hypervisor architecture has direct access to the hardware resources, rather than going through the Operating System which make it more efficient than hosted architecture. This delivers greater scalability, robustness and performance. A hypervisor is the primary component of virtualisation that enables basic computer system partitioning i.e. simple partitioning of CPU, memory and I/O. VMware ESX/ESXi employs a bare-metal hypervisor architecture on certified hardware for datacenter-class performance.
WHAT IS A VIRTUAL MACHINE
From a user's perspective, a virtual machine is a software platform that like a physical computer runs an operating system and applications.
From Hypervisor's perspective, a virtual machine is a discrete set of files. The main files are as below;
- Configuration file
-Virtual disk file
- NVRAM settings file
-Log file
WHY VIRTUALISATION
Virtual machines have many advantages over physical machines.
Virtual machines are easy to move and copy across different hosts.
Encapsulated into files.
Independent of Physical hardware.
Isolated from othr virtual machines.
Insulated from hardware changes.
Provides the ability to support legacy applications.
Allows server to be consolidated.
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