sysad323 virtualization basics

VIRTUALIZATION BASICS

What is Virtualization?

• Virtualization is the creation of a virtual (rather than actual) version of something, such as an operating system, a server, a storage device or network resources.

• Virtualization allows a single physical resource (such as a server, operating system, application, or storage device) to function as multiple logical resources.

History• Virtualization was first developed in the 1960s to partition

large, mainframe hardware for better hardware utilization. Today, computers based on x86 architecture are faced with the same problems of rigidity and underutilization that mainframes faced in the 1960s. VMware invented virtualization for the x86 platform in the 1990s to address underutilization and other issues, overcoming many challenges in the process. Today, VMware is the global leader in x86 virtualization, with over 150,000 customers, including 100% of the Fortune 100.

Areas of I.T. Virtualization

• Operating system virtualization is the use of software to allow a piece of hardware to run multiple operating system images at the same time. The technology got its start on mainframes decades ago, allowing administrators to avoid wasting expensive processing power.


• Network virtualization is a method of combining the available resources in a network by splitting up the available bandwidth into channels.

• Each channel can be assigned (or reassigned) to a particular server or device in real time.

• Virtualization disguises the true complexity of the network by separating it into manageable parts that can be used by other virtualized assets (eg. Servers and Storage).


• Technology allows for the consolidation of several physical computers, each running a single OS and application(s), to fewer physical computers running one or more "Virtual Servers" on each physical computer.

• Virtual servers (also known as Virtual machines) include the complete OS (usually MS Windows or Linux) and the application(s) that run on the OS.

• Example: 20 physical computers reduced to 4 physical computers, each with 5 Virtual servers (OS and application).

• Latest technology allows Virtual Servers to migrate between physical computers (nodes) depending on performance or business continuity requirements.


• Storage virtualization is the pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console.

• Storage virtualization is commonly used in storage area networks.

• Storage Area Networks (SANs) are usually connected to servers via Fibre Channel or other high-speed link, allowing storage performance to equal direct-attach storage.

• SANs or other network-based storage systems are key components for server virtualization.

Why Use Virtualization?

• Consolidation – It means combining multiple software

workloads on one computer system. – You can run various virtual machines in order

to save money and power (electricity). – Implementation of virtualization results in a

significant reduction in hardware and maintenance costs.


• Testing – You can test various configuration.– You can create less resource hungry and low priority

virtual machines (VM). Often, – This is also good for students who wish to learn new

operating systems and programming languages / database without making any changes to working environment.


• Security and Isolation – If mail server or any other app gets cracked,

only that VM will be under control of the attacker.

– Also, isolation means misbehaving apps (e.g. memory leaks) cannot bring down whole server

Open Source Linux Virtualization Software

OpenVZ is an operating system-level virtualization technology based on the Linux kernel and operating system.


Xen is a virtual machine monitor for 32 / 64 bit Intel / AMD (IA 64) and PowerPC 970 architectures. It allows several guest operating systems to be executed on the same computer hardware concurrently. XEN is included with most popular Linux distributions such as Debian, Ubuntu, CentOS, RHEL, Fedora and many others.


Kernel-based Virtual Machine (KVM) isa Linux kernel virtualization infrastructure. KVM currently supports Native virtualization using Intel VT or AMD-V. A wide variety of guestoperating systems work with KVM, including many flavors of Linux, BSD, Solaris, and Windows etc. KVM is included with Debian, OpenSuse and other Linux distributions.


Linux-VServer is a virtual private server implementation done by adding operating system-level virtualization capabilities to the Linux kernel


• VirtualBox is an x86 virtualization software package, developed by Sun Microsystems as part of its Sun xVM virtualization platform. Supported host operating systems include Linux, Mac OS X, OS/2 Warp, Windows XP or Vista, and Solaris, while supported guest operating systems include FreeBSD, Linux, OpenBSD, OS/2 Warp, Windows and Solaris.


• Bochs is a portable x86 and AMD64 PC emulator and debugger. Many guest operating systems can be run using the emulator including DOS, several versions of Microsoft Windows, BSDs, Linux, AmigaOS, Rhapsody and MorphOS. Bochs can run on many host operating systems, like Windows, Windows Mobile, Linux and Mac OS X.


• User Mode Linux (UML) was the first virtualization technology for Linux. User-mode Linux is generally considered to have lower performance than some competing technologies, such as Xen and OpenVZ. Future work in adding support for x86 virtualization to UML may reduce this disadvantage

Proprietary Linux Virtualization Software

• VMware Server (also known as GSX Server) is an entry-level server virtualization software. VMware ESX Server is an enterprise-level virtualization product providing data center virtualization. It can run various guest operating systems such as FreeBSD, Linux, Solaris, Windows and others


• XenServer is based on the open source Xen hypervisor, an exceptionally lean technology that delivers low overhead and near-native performance.

• Oracle VM is based on the open-source Xen hypervisor technology, supports both Windows and Linux guests and includes an integrated Web browser based management console. Oracle VM features fully tested and certified Oracle Applications stack in an enterprise virtualization environment


• The xVM Server uses a bare-metal hypervisor based on the open source Xen under a Solaris environment on x86-64 systems. On

• SPARC systems, xVM is based on Sun's Logical Domains and Solaris. Sun plans to support Microsoft Windows (on x86-64 systems only), Linux, and Solaris as guest operating systems.


• Parallels Virtuozzo Containers - It is an operating system-level virtualization product designed for large-scale homegenous server environments and data centers. Parallels Virtuozzo Containers is compatible with x86, x86-64 and IA-64 platforms. You can run various Linux distributions inside Parallels Virtuozzo Containers.

Virtualization - terms

• a hypervisor, also called virtual machine monitor (VMM), is a piece of software/hardware platform-virtualization software that allows multiple operating systems to run on a host computer concurrently.

sysad323 virtualization basics

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