BLADE SERVER TECHNOLOGY - HOT TOPIC - Virtualization

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Virtualization Technology Overview

Virtualization has become an important blade server technology because it provides the ability to improve server consolidation, increase efficiency, simplify management and improve performance in the blade server environment.

According to the Yankee Group, 9 out every 10 large enterprises will have implemented virtualization into their IT infrastructure by end of 2007. IDC predicts 69% of servers purchased in 2006-2007 were virtualized compared to just 7% of the existing worldwide base. The formal IDC study, Worldwide Virtualization Services 2007 Ð 2001 Forecast, predicts the virtualization services market will grow from $5.5 billion in 2006 to $11.7 billion in 2011. Gartner analyst Thomas Bittman said in May, 2007 that the number of virtual machines in use will rise from 500,000 in 2006 to three million by 2009. Gartner analyst Phil Sargent added that virtualization will be part of nearly every aspect of IT by 2015.

So what is virtualization and why has it become so important?

Server virtualization is an abstraction technology that enables the division of the hardware resources of a given server into multiple execution environments and enables the consolidation of multiple servers and hardware resources into a single computing resource.

There are several good reasons why this technology is valuable in a data center environment. Virtual machines created through virtualization software can:

consolidate the workloads of several servers into one, higher performance server
create the illusion of legacy hardware so that investments in existing software/hardware infrastructures can be maintained even as a data center migrates to newer, more productive and higher performance hardware configurations
be used to run multiple operating systems and applications simultaneously, increasing the flexibility and utility of a given set of data center resources
enable the isolation of applications within a single server/server complex so that runaway applications do not bring down the entire server infrastructure
give data center managers a simplified infrastructure management control point that gives better control over the common tasks of server provisioning, backups and disaster recovery, and system migration

Today, the data center manager is facing an unrelenting and ever increasing demand for more server productivity while being squeezed by financial and physical limitations as corporate managers see IT equipment costs increasing as a percentage of overall costs. In trying to do more in the data center with less, or at least more with a lower cost of acquisition and maintenance, the IT manager has increasingly turned to blade servers and virtualization technologies to increase data center productivity, flexibility and accrue savings in hardware acquisition, environmental costs and administration of the data center.

How Virtualization Works

Virtualization is using software to create a "virtual machine" that is an abstraction of real computer hardware that gives a single server the ability to act as if it were multiple machines. The software that manages this process is commonly called a Virtual Machine Monitor and it creates virtual machines and manages the control system that allows these virtual machines to access the underlying hardware.

In the past, virtualization has been almost an entirely software-based technology. Recently, server processor makers have implemented hardware resources on-chip in the server processors that enable software virtualization vendors to optimize their offering for greater performance and security. Virtualization software vendors have moved quickly to take advantage of the superior performance made possible by virtualization-friendly hardware features now embedded in the most advanced server processors. But, their use doesnÕt fundamentally change the nature of virtualization technology.

Server virtualization uses software to create a layer between the real computing resources of a server, the hardware and the OS and builds a virtual server upon which standard application programs run. The software that manages the interface between the virtual machines and the underlying server platform is called the Virtual Machine Monitor or hypervisor and the simulated hardware platforms it creates are called virtual machines. Virtual machines simulate the hardware platform and allows a guest OS to be run separately from the rest of the real server platform. For example, a real server system may be running a Linux OS and a virtualization hypervisor. The VMM or hypervisor can create a virtual machine instance that runs Windows or any other OS simultaneously. For the end user, running applications on a virtual machine, it seems that there is only one machine, his own, with a single OS and single hardware platform.

Blade.org member VMware is a leading provider of virtualization software and as shown in Figure 1 below, the VMware Infrastructure is built upon the ESX Server platform (a hypervisor) and multiple virtual machines. In addition, there are additional features included in ESX Server such as Virtual SMP that support multiprocessing and VMFS, a high performance cluster file system for storage virtualization. A VirtualCenter Management Server provides for centralized management and automation. Other functions that extend ESX Server functionality include modules for high availability, dynamic load balancing and resource allocation, live migration of virtual machines without service disruption and centralized backup for virtual machines.

VMware Diagram

VMware ESX Server hypervisor installs on the "bare metal" of a server hardware platform and gives the IT manager the ability to install and run multiple unmodified operating systems and their application in the virtual machines created in ESX Server. Each virtual machine acts as a complete server system, with its own processor, memory, networking, storage and BIOS resources. The management capabilities of the ESX Server give the IT manager the ability to set allocation policies that determine the resource allocation so that critical applications can be given the necessary resources whenever they are needed. The Virtual SMP capabilities allow enterprise-class, mission-critical applications to be supported in the virtual machine environment. VMware technology pools physical computing resources into a single computing resource, allocated via policies to the appropriate application.

Running under a set of Windows OSs, VMware VirtualCenter Management Server enables the management of multiple ESX host (separate real server platforms) and the many virtual machines that may run on those resources. It consolidates the physical resources of all of the platforms and interfaces to each physical host and maintains a database of host configurations, virtual machine characteristics, statistics, alarms, user permissions and all of the other information needed to manage multiple machines. It simplifies management tasks by providing wizard-driven templates that enable the creation and deployment of new virtual machines in seconds, provides for task scheduling and automatic alerts, and automation of routine management tasks.

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