Issue No. 50Sept 2016

Server Virtualization: How it works 

Virtualization 101

A challenge facing all organizations who host and manage their own computer servers are the limitations inherent in the server’s hardware architecture. Generally, servers are designed to run just one operating system and application at a time. As a result, it has been necessary to deploy many servers to support a company’s needs, with each server typically operating at just 5 to 15 percent of capacity. This is highly inefficient by any standard.
Virtualization uses software to emulate the existence of hardware, and create a virtualized computer. Doing this allows businesses to run more than one virtualized system in parallel, and therefore multiple operating systems and applications can be running on a single physical server. This can provide economies of scale and greater efficiency.

The Virtual Machine

A virtualized computer system is known as a “virtual machine” (VM):  A tightly isolated software container with an independent operating system and application inside the isolated container. Each self-contained VM is completely independent of one another. Putting multiple VMs on a single computer enables several operating systems and applications to run on just one physical server, or “host” server.

A thin layer of software called a hypervisor divides the virtual machines from the host server and dynamically allocates computing resources to each virtual machine as needed.

**Key Properties of Virtual Machines

VM’s have the following characteristics, which offer several benefits

Partitioning

• Run multiple operating systems on one physical machine
• Divide system resources between virtual machines

Isolation

• Provide fault tolerance and system isolation at the hardware level
• Preserve performance with advanced resource controls

Encapsulation

• Save the entire state of a virtual machine to files
• Move and copy virtual machines as easily as moving and copying files

Hardware Independence

• Provision or migrate any virtual machine to any physical server

Server Consolidation

• Using server virtualization, a company can maximize the use of its server resources and reduce the number of servers required. The result is server consolidation, which improves efficiency and cuts costs.