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Introduction to Virtualization

Post by :    Date : 2014-11-30 02:03:40

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Introduction to Virtualization

Virtualization is a generic umbrella term what an include anything's from social networks to simulated realties. For us the context is Data Center Virtualization encompassing Server, Network, Storage and Firewall Virtualization.

What is a Hypervisor?

Hypervisor or Virtual Machine Monitor (VMM) a piece of software which is responsible for the life-cycle of a Virtual Machine. Virtual Machine is a guest OS running on a hypervisor with all the required resources ( CPU, RAM, HDD, NICs, etc).

Types of Hypervisors

Type 1 or Bare-Metal

- Runs on the Metal 
- Very low overhead 
- VMware ESXi &  ESX, Citrix Xen, Microsoft Hyper-V

Type 2 or Hosted

- Hypervisor is an application running on a base OS 
- Overhead due to the base OS 
- VMware Workstation & Fusion, Sun/Oracle Virtual Box, Microsoft VirtualPC and Parallels 

Hosted vS Bare-Metal

What lead to the adoption of Virtualization ?

- Low usage of provisioned hardware resources - An industry survey found that only 20% of the available resources are consumed - Speed and Agility - Server take weeks to provision


- VM’s assigned resources can be changed as required with just a couple of mouse clicks 
- VMs can be moved between servers for hardware maintenance without any downtime 
- High Availability can be used to protect the VMs in case of hardware failures. 
- Hardware resources can be efficiently used by balancing the VMs among the hypervisors in the cluster.

Computing Models

Traditional Model

- One OS owns the hardware 

- Application load vary

- Required power and cooling 

- Hardware maintenance require downtime 

- If the application needs more resources ? 


Virtualized Model

- Multiple OSes share the hardware 
- Resources utilization increase 
- Reduced cooling and power costs  
- Hardware maintenance requires no downtime 
- New hardware can be added to the VMs as required. 

Before Virtualization

- Single OS image per machine 
- Software and hardware tightly coupled 
- Running multiple application on same machine often creates conflict 
- Underutilized resources  
- Inflexible and costly infrastructure 

After Virtualization

- Hardware-independence of operating system and applications 
- Virtual machines can be provisioned to any system 
- can manage OS and application as a single unit by encapsulating them into virtual machines

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