Virtualization is one of the fundamental technologies in cloud computing. Critical in infrastructure based services. It is combination of Software and Hardware that allows to emulate underlying Technology stacks that in turn allows applications to execute. For example, you can have an instance of Windows machine installed on Linux hardware. This kind of capability provides flexibility to have high end Hardware hosting multiple instances of heterogeneous operating system instances.
Fig- Windows OS hosted on Linux Machine
- Virtualization offered main have hardware virtualisation, which plays a fundamental role in infrastructure as a services(Iaas) solutions for cloud computing.
- Virtualizations Technologies provide a vital environment for not only executing applications but also for storage, memory and networking.
- Some of the reasons for virtualizations to gain prominence are as below.
- Increase in performance and storage capacities - over the years, research and development in hardware have bought down costs of memory/storage drastically down.
- Need to better utilise available hardware and software resources - with increased capacities, hardware and software resources are being and utilised at multiple levels. Sporadic need for resources due to some surge in activities renders these resources Idol on other times.
- Lack of space - continuously increasing new hardware in premises ads to challenge of space. Maintaining these hardware elements is also huge overhead.
- Green initiatives - companies are looking for ways to consume less energy thereby reducing their carbon footprint.
- Administrative costs - you need power to keep devices running and when you run, you also need power to ensure that operating temperatures are at required levels. These requirements add to administrative costs.
Characteristics of virtualized environments
Virtualisation at any level is achieved by means of software programs. This provides with advantages these were not a possible earlier. These advantages represent characteristics of virtualized environment.
1. Increased seurity
- All the execution is that happen on virtual environment are always in context of virtual machine that is hosted on guest machine. This means, any activity performed on VM, is filtered by VM software before part of it is executed on host this gives better control and protection to host machine.
- Resources on host can be protected from guest.
- File system provided by virtual machine is completely separated from host file system access to host storage is not possible unless specially configured.
2. Managed execution
working in virtual environment not only provides increased security but also their benefits like sharing, aggression, immunization and isolation.
- Sharing
- multiple virtual environments can be hosted on single host machine.
- This allows full utilisation of power host machine.
- Aggression
- multiple physical resources can be tied together to perform actions on single host.
- Opposite process of sharing.
- Eg. Cluster management software
- Emulation
- Best programs are executed within an environment that is controlled by the virtualisation layer, which ultimately is a program.
- Eg. Windows host machine cannot run a virtual environment that execute Linux virtual machine.
- This feature is very useful in testing.
- Isolation
- provides guest with a complete separate environment, in which they are executed.
- The guest program performs its activity by interacting with an abstraction layer, that intern provides access to the underlying resources.
3. Performance tuning
- This allows to perform performance tested by fine tuning capability of virtual environment.
- With advent of high end Hardware capabilities, it is possible to get virtual environment setup and configured to our liking.
- It is possible to configure virtual machine with specific amount of RAM in order to test software performance on low memory machines.
4. portability
portability allows having own system always with you and ready to use as long as the required Virtual Machine manager is available.
