Virtualization in computing is the creation of a virtual version of something, such as a hardware platform, operating system, a storage device or network resources. Virtualization is software technology which uses a physical resource such as a server and divides it up into virtual resources called virtual machines (VM’s). Virtualization allows users to consolidate physical resources, simplify deployment and administration, and reduce power and cooling requirements. A virtual machine (VM) is a software implementation of a computing environment in which an operating system (OS) or program can be installed and run.
Virtual machines can provide numerous advantages over the installation of OS’s and software directly on physical hardware. VMs can also be easily moved, copied, and reassigned between host servers to optimize hardware resource utilization.
Virtualization in its simplest form is the abstraction of hardware from the software. This can take many forms. It can be in the form of operating system virtualization such as Hyper-V; presentation virtualization with terminal services; or application virtualization with App-V; and companies like Cisco and Hewlett Packard have network and storage virtualization.
Operating system virtualization is the most popular virtualization today. It is not only used on servers but is installed on workstations for doing development and conducting demonstrations. Virtualization can help companies maximize the value f IT investments, decreasing the server hardware footprint, energy consumption, and cost and complexity of managing IT systems while increasing the flexibility of the overall environment. Virtualization also helps IT professionals and developers build systems with the flexibility and intelligence to automatically adjust to changing business conditions by aligning computing resources with strategic objectives.
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What is Virtualization
Virtualization is a fundamental technological innovation that allows skilled IT managers to deploy creative solutions to such business challenges. Virtualization technology is possibly the single most important issue in IT and has started a top to bottom overhaul of the computing industry. The growing awareness of the advantages provided by virtualization technology is brought about by economic factors of scarce resources, government regulation, and more competition.
Virtual machines can be used to consolidate the workloads of several under-utilized servers to fewer machines; perhaps a single machine. The need to run legacy applications is served well by virtual machines. Virtual machines can be used to provide secure, isolated sandboxes for running un trusted applications. Virtual machines can be used to create operating systems, or execution environments with resource limits, and given the right schedulers, resource guarantees. These provide the illusion of hardware, or hardware configuration that you do not have such as multiple processors etc. Virtualization can also be used to simulate networks of independent computers. Virtual machines can be used to run multiple operating systems simultaneously: different versions, or even entirely different systems, which can be on hot standby. Virtual machines allow for powerful debugging and performance monitoring. Virtualization can enable existing operating systems to run on shared memory multiprocessors.
A hypervisor, also called a virtual machine manager, is a program that allows multiple operating systems to share a single hardware host. Each operating system appears to have the host’s processor, memory, and other resources all to itself. However, the hypervisor is actually controlling the host processor and resources’, allocating what is needed to each operating system in turn and making sure that the guest operating systems (called virtual machines) cannot disrupt each other.
There are two major types of hypervisors; a monolithic hypervisor and a microkernel-zed hypervisor. The monolithic hypervisor is installed directly to hardware and holds all third-party tools and drivers required for the Admin VM and guest VMs to function. A microkernel-zed hypervisor, like the monolithic hypervisor, is installed directly to the hardware but offloads driver management and the virtualization stack to the parent partition.
Virtualization brought in an era of consolidation and better control over the infrastructure. It provided an opportunity to create a more secure environment.
Every virtualization solution today talks about the hypervisor-that represents the primary abstraction layer between physical hardware and the virtual machines (VMs) running in any virtualized platform as depicted in the figure below:
Every virtualization platform provides the tools that assist system administrators to migrate an active VM to other live physical servers without any interruption. The VM is essentially a file or an image stored on a hard disk. These VMs can be accessed offline by remounting the image.
The reigning king in the world of virtualization is VMware. . VMware is the leading business virtualization infrastructure provider, offering the most trusted and reliable platform for building private clouds and federating to public cloud.
VMware, Inc. Is a company providing virtualization software founded in 1998 and based in Palo Alto, California, USA. The company was acquired by EMC Corporation in 2004, and operates as a separate software subsidiary. VMware’s desktop software runs on Microsoft Windows, Linux, and Mac OS X, while VMware’s enterprise software hypervisors for servers, VMware ESX and VMware ESXi, and are bare-metal embedded hypervisors that run directly on server hardware without requiring an additional underlying operating system. VMware became well known for their first type 2 hypervisor known as GSX. This product has since evolved into two hypervisor products lines, VMware’s type 1 hypervisors running directly on hardware, along with their hosted type 2 hypervisors.
VMware software provides a completely virtualized set of hardware to the guest operating system. VMware software virtualizes the hardware for a video adapter, a network adapter, and hard disk adapters. The host provides pass-through drivers for guest USB, serial, and parallel devices. In this way, VMware virtual machines become highly portable between computers, because every host looks nearly identical to the guest. A system administrator can pause operations on a virtual machine guest, move or copy that guest to another physical computer, and there resume execution exactly at the point of suspension,
VMware’s products predate the virtualization extensions to the x86 instruction set, and do not require virtualization-enabled processors. VMware operates dramatically faster than emulators, running at more than 80% of the speed that the virtual guest operating-system would run directly on the same hardware. VMware software does not emulate an instruction set for different hardware not physically present. This significantly boosts performance but can cause problems when moving virtual machine guests between hardware hosts using different instruction-sets (such as found in 64-bit Intel and AMD CPUs), or between hardware hosts with a differing number of CPUs.
ESX Server is a component of VMware’s VMware Infrastructure, which adds management and reliability services to its core server product. The basic server requires some sort of storage, like an array of disk drives, for storing the virtualized kernel and support files. VMware offers a variant of this product called ESX Server ESXi Embedded. This moves all the server’s kernels into a dedicated hardware device. In the VMware world, they refer to the hypervisor used as a VMkernel.
ESX Server sets up a Linux kernel first, and that kernel is used to load specialized virtualization components, including VMkernel. That first installed Linux kernel becomes the first running virtual machine and is called the service console.
The VMkernel has three interfaces with the user:
Access to other hardware is accomplished using this interface.
This interface simulates hardware and occurs in such a way that a guest system itself can run unmodified on top of the hypervisor.
VMware Infrastructure 3 (VI3) is a solution aimed at enterprises that are looking to consolidate full-scale production systems. It is the most scalable of the VMware platforms with new management, load-balancing, and high-availability features. As VI3 is based on ESX Server, it is not dependent on a host operating system, and it can be used to host virtual machines running Windows, Linux, or other common operating systems. Since VI3 is so scalable, it can run up to 128 concurrent virtual machines on multiple ESX servers, all managed from a central console. Those servers can all be configured to share a common file system-the VMware Virtual Machine Fine System (VMFS)-hosted on local disks, Network Attached Storage (NAS), or Storage Area Network (SAN) storage. VMFS makes provisioning and management of virtual machines much simpler. It makes it possible to dynamically allocate resources and profess loads across both virtual machines and physical servers. It is possible to move an entire virtual machine from one server to another, even while users and applications are actively using it. Additionally, once the virtual machines are installed, they can be managed remotely. VI3 employs the VMware Distributed Resource Scheduler (DRS), which automatically tunes processor, memory, and other resources. VMware High Availability (HA) adds automatic failover if there is a hardware or software problem and VMotion makes it possible to migrate live virtual machines from one server to another. This aids in maintenance and load balancing.
VMware vSphere is the industry’s most complete, scalable and powerful virtualization platform, delivering the infrastructure and application services that organizations need to transform their information technology and deliver IT as a service
What is VMware vSphere?
VMware vSphere is the industry’s most complete, scalable and powerful virtualization platform, delivering the infrastructure and application services that organizations need to transform their information technology and deliver IT as a service. Proven by more than 170,000 customers-including all the Fortune Global 100-and leveraging more than a decade of industry-leading technology and experience, vSphere provides unparalleled agility, control and efficiency while fully preserving customer choice.
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How is vSphere used?
Consolidate and optimize IT hardware-vSphere enables IT organizations to delay costly and disruptive datacenter expansion projects by making it possible to consolidate 15 or more virtual machines on a single physical server without sacrificing performance or throughput. Improve business continuity, vSphere helps organizations reduce the cost and complexity of business continuity and disaster recovery with always-on IT capabilities and layered protection against service outages and data loss. Streamline IT operations-vSphere lowers operational overhead and dramatically simplifies the management of large, geographically distributed development, QA and production IT environments. Deliver IT as a service-VMware vSphere is the only virtualization platform that gives customers the power to realize the benefits of cloud computing while maintaining security, compliance and complete control over corporate assets.
Key Features and Components
VMware ESXi™ and ESX® hypervisor architectures provide a robust, production-proven, high-performance virtualization layer that allows multiple virtual machines to share hardware resources with record-breaking performance that can match and in some cases exceed) native throughput.
VMware Virtual SMP enables the use of ultra-powerful virtual machines that possess up to four virtual CPUs.
VMware vStorage Virtual Machine File System (VMFS) allows virtual machines to access shared storage devices (FibreChanel, iSCSI, etc.), and is a key enabling technology for other vSphere components such as Storage vMotion.
VMware vMotion™ eliminates the need to schedule application downtime due to scheduled server maintenance through live migration of virtual machines across servers with no disruption to users or loss of service.
VMware High Availability (HA) provides cost effective, automated restart within minutes for all applications in the event of hardware or operating system failures.
Hot plug virtual storage and network devices to or from virtual machines without disruption or downtime.
Additional vSphere Products and Add-Ons
VMware vCenter Server-vCenter Server provides unified management for the entire virtual infrastructure and unlocks many key vSphere capabilities such as live migration. VCenter Server can manage thousands of virtual machines across multiple locations and streamlines administration with features such as rapid provisioning and automated policy enforcement.
VMware vSphere 5, the industry-leading virtualization platform for building cloud infrastructures, enables to run business critical applications with confidence and respond to the business faster.
Virtualization is not primarily about cost-cutting. Strategically, virtualization leads inexorably down a path toward flexible sourcing, and cloud computing. Even our surveys show that organizations who are well on their way toward virtualization change their points of view – flexibility, agility, speed move to the top of the list.
There are few things that virtualization does to unlock the door to cloud computing, and push organizations faster in that direction.
Speed, flexibility, agility:
Early adopters of cloud computing talk about how quickly they can get new servers online. Compared to the 4-6 weeks it takes an average IT shop to deploy a server, just about anything is faster. However, virtual machines can be deployed roughly 30 times faster. It doesn’t take a cloud to improve speed. And, of course, operational processes and management tools need to change to deal with speed. And speed changes business expectations and behavior – it changes culture.
Virtualization is a computing technology that enables a single user to access multiple physical devices. Another way to look at it is a single computer controlling multiple machines, or one operating system utilizing multiple computers to analyze a database. Virtualization may also be used for running multiple applications on each server rather than just one; this in turn reduces the number of servers companies need to purchase and manage.
Cloud computing offers scalable infrastructure and software off site, saving labor, hardware, and power costs. Financially, the cloud’s virtual resources are typically cheaper than dedicated physical resources connected to a personal computer or network. With cloud computing, the software programs you use aren’t run from your personal computer, but rather are stored on servers housed elsewhere and accessed via the Internet.
One way to look at it is that virtualization is basically one physical computer pretending to be many computing environments whereas cloud computing is many different computers pretending to be the one computing environment (hence user scaling). Virtualization provides flexibility that is a great match for cloud computing. Moreover, cloud computing can be defined based on the virtual machine containers created with virtualization. Virtualization is not always necessary in cloud computing; however, you can use it as the basis. Cloud computing is an approach for the delivery of services while virtualization is one possible service that could be delivered. Large corporations with little downtime tolerance and airtight security requirements may find that virtualization fits them best. Smaller businesses are more likely to profit more with cloud computing, allowing them to focus on their mission while leaving IT chores to those who can do more for less.
Plainly, virtualization provides more servers on the same hardware and cloud computing provides measured resources while paying for what you use. While it is not uncommon to hear people discuss them interchangeably, they are very different approaches to solving the problem of maximizing the use of available resources. They differ in many ways and that also leads to some important considerations when selecting between the two.
Virtualization is the creation of substitutes for real resources, i.e substitutes that have the same functions and external interfaces as their counterparts, but that differ in attributes, such as size, performance, and cost.
When you think about applying virtualization to your current environment, you must think about consolidating logical resources rather than physical resources into a system designed to support server, storage, and network virtualization. By adding any of these virtualization technologies to your environment, you create an on demand, secure, and flexible infrastructure prepared to handle workload changes in your environment.
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