VIRTUALIZATION-Basics & Applications
Abstract:
Start by eliminating the old “one server, one application” model and run multiple virtual machines on each physical machine. Improve the efficiency and availability of IT resources and applications through virtualization. Free your IT admins from spending so much time managing servers rather than innovating. About 70% of a typical IT budget in a non-virtualized datacenter goes towards just maintaining the existing infrastructure, with little left for innovation.
Today’s x86 computer hardware was designed to run a single operating system and a single application, leaving most machines vastly underutilized. Virtualization lets you run multiple virtual machines on a single physical machine, with each virtual machine sharing the resources of that one physical computer across multiple environments. Different virtual machines can run different operating systems and multiple applications on the same physical computer. While others are leaping aboard the virtualization bandwagon now, VMware is the market leader in virtualization. Our technology is production-proven, used by more than 170,000 customers, including 100% of the Fortune 100.
Definition:
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.
How Does Virtualization Work?
The VMware virtualization platform is built on a business-ready architecture. Use software such as VMware vSphere to transform or “virtualize” the hardware resources of an x86-based computer—including the CPU, RAM, hard disk and network controller—to create a fully functional virtual machine that can run its own operating system and applications just like a “real” computer. Each virtual machine contains a complete system, eliminating potential conflicts. VMware virtualization works by inserting a thin layer of software directly on the computer hardware or on a host operating system. This contains a virtual machine monitor or “hypervisor” that allocates hardware resources dynamically and transparently. Multiple operating systems run concurrently on a single physical computer and share hardware resources with each other. By encapsulating an entire machine, including CPU, memory, operating system, and network devices, a virtual machine is completely compatible with all standard x86 operating systems, applications, and device drivers. You can safely run several operating systems and applications at the same time on a single computer, with each having access to the resources it needs when it needs them.
Virtualization can run in two ways :
1.Virtualization on host OS
2.Virtualization without host OS
Using Virtualization to Host Multiple Operating Systems
In many cases,virtualization is used to create many Virtual Private servers(VPS), which essentially make small duplicates of the same operating system within directories that appear to the user as servers within themselves.
In virtualization,the host OS is the primary one installed on your server.You then install the virtualization software within that OS. Finally, you must install the guest OS within a virtual machine. Unlike emulation,virtualization software does not usually emulate hardware. Infact,in some cases, it directly interfaces with the server’s hardware, giving you real-time performance(essentially like running the two OS side-by-side, rather than one on top of the other).with this setup, it is possible to run two distinct OS with different web server software, different scripting languages and different web applications, all within the same physical box.
OS virtualization: Virtualizing without the hypervisor
Virtualization doesn't require a hypervisor. Imagine a virtualization infrastructure completely devoid of a hypervisor. Having no hypervisor eliminates the need for driver emulation. Getting rid of driver emulation means faster performance. Faster performance means more virtual machines that can be run simultaneously. And more simultaneous virtual machines nets you higher density, all of which means more bang for your virtualization dollar.
Applications:
1.Hardware Virtualization
2.Network Virtualization
3.I/O Virtualization
4.Memory Virtualization
Hardware Virtualization:
Hardware virtualization is when the virtual machine manager is embedded in the circuits of a hardware component instead of being called up from a third-party software application. The virtual machine manager is called a hypervisor.
The job of the hypervisor is to control processor, memory and other firmware resources. The hypervisor acts like a traffic cop, allowing multiple operating systems to run on the same device without requiring source code or binary changes. Each operating system appears to have the processor, memory, and other firmware resources all to itself -- but in reality, the hypervisor is controlling the processor and its resources, allocating what is needed to each operating system in turn.
Hardware virtualization is a system which uses one processor to act as if it were several different computers. This has two main purposes. One is to run different operating systems on the same hardware. The other is to allow more than one user to use the processor at the same time. While there are both logistical and financial benefits to hardware virtualization, there are still some practical limitations.
The name hardware virtualization is used to cover a range of similar technologies carrying out the same basic function. Strictly speaking, it should be called hardware-assisted virtualization. This is because the processor itself carries out some of the virtualization work. This is in contrast to techniques which are solely software based.
The primary use of hardware virtualization is to allow multiple users to access the processor. This means that each user can have a separate monitor, keyboard and mouse and run his or her OS independently. As far as the user is concerned, they will effectively be running their own computer. This set-up can cut costs considerably as multiple users can share the same core hardware.
There are some significant limitations to hardware virtualization. One is that it still requires dedicated software to carry out the virtualization, which can bring additional costs. Another is that, depending on the way the virtualization is carried out, it may not be as easy to add in extra processing power later on as and when it is needed. Perhaps the biggest drawback is that no matter how efficiently the virtualization is carried out, the maximum processing power of the chip cannot be exceeded. This means it must be split between the different users.
Network Virtualization:Network virtualization is a method of combining the available resources in a network by splitting up the available bandwidth into channel, each of which is independent from the others, and each of which can be assigned (or reassigned) to a particular server or device in real time. Each channel is independently secured. Every subscriber has shared access to all the resources on the network from a single computer.
Network management can be a tedious and time-consuming business for a human administrator. Network virtualization is intended to improve productivity, efficiency, and job satisfaction of the administrator by performing many of these tasks automatically, thereby disguising the true complexity of the network. Files, images, programs, and folders can be centrally managed from a single physical site. Storage media such as hard drives and tape drives can be easily added or reassigned. Storage space can be shared or reallocated among the servers.
Network virtualization is intended to optimize network speed, reliability, flexibility, scalability, and security. Network virtualization is said to be especially effective in networks that experience sudden, large, and unforeseen surges in usage.
Memory Virtualization:
A guest operating system that executes within a virtual machine expects a zero-based physical address space, as provided by real hardware. ESX Server gives each VM this illusion, virtualizing physical memory by adding an extra level of address translation. A machine address refers to actual hardware memory, while a physical address is a software abstraction used to provide the illusion of hardware memory to a virtual machine. We will often use ``physical'' in quotes to highlight this deviation from its usual meaning.
In computer science, memory virtualization decouples volatile random access memory (RAM) resources from individual systems in the data center, and then aggregates those resources into a virtualized memory pool available to any computer in the cluster. The memory pool is accessed by the operating system or applications running on top of the operating system. The distributed memory pool can then be utilized as a high-speed cache, a messaging layer, or a large, shared memory resource for a CPU or a GPU application.
Memory virtualization allows networked, and therefore distributed, servers to share a pool of memory to overcome physical memory limitations, a common bottleneck in software performance. With this capability integrated into the network, applications can take advantage of a very large amount of memory to improve overall performance, system utilization, increase memory usage efficiency, and enable new use cases. Software on the memory pool nodes (servers) allows nodes to connect to the memory pool to contribute memory, and store and retrieve data. Management software manages the shared memory, data insertion, eviction and provisioning policies, data assignment to contributing nodes, and handles requests from client nodes. The memory pool may be accessed at the application level or operating system level. At the application level, the pool is accessed through an API or as a networked file system to create a high-speed shared memory cache. At the operating system level, a page cache can utilize the pool as a very large memory resource that is much faster than local or networked storage.
Memory virtualization implementations are distinguished from shared memory systems. Shared memory systems do not permit abstraction of memory resources, thus requiring implementation with a single operating system instance (i.e. not within a clustered application environment).
I/O Virtualization:
Input/output (I/O) virtualization is a methodology to simplify management, lower costs and improve performance of servers in enterprise environments. I/O virtualization environments are created by abstracting the upper layer protocols from the physical connections.
The technology enables one physical adapter card to appear as multiple virtual network interface cards (vNICs) and virtualhost bus adapters (vHBAs). Virtual NICs and HBAs function as conventional NICs and HBAs, and are designed to be compatible with existing operating systems, Hypervisors, and applications. To networking resources (LANs and SANs), they appear as normal cards.
In the physical view, virtual I/O replaces a server’s multiple I/O cables with a single cable that provides a shared transport for all network and storage connections. That cable (or commonly two cables for redundancy) connects to an external device, which then provides connections to the data center networks.
Benefits of I/O Virtualization:
- Management agility: By abstracting upper layer protocols from physical connections, I/O virtualization provides greater flexibility, greater utilization and faster provisioning when compared to traditional NIC and HBA card architectures.
- Reduced cost: Virtual I/O lowers costs and enables simplified server management by using fewer cards, cables, and switch ports, while still achieving full network I/O performance.
- Reduced cabling: In a virtualized I/O environment, only one cable is needed to connect servers to both storage and network traffic. This can reduce data center server-to-network, and server-to-storage cabling within a single server rack by more than 70 percent, which equates to reduced cost, complexity, and power requirements. Because the high-speed interconnect is dynamically shared among various requirements, it frequently results in increased performance as well.
- Increased density: I/O virtualization increases the practical density of I/O by allowing more connections to exist within a given space. This in turn enables greater utilization of dense 1U high servers and blade servers that would otherwise be I/O constrained.
Virtualization Tools:
10 Free Virtualization Tools You Should Know
- OpenVZ
- FreeVPS
- Sun xVM
- VirtualBox
- PlateSpin Power Recon
- Vizioncore vOptimizer Free Ware
- Virtual Iron Single Server Edition
- Enomalism Virtualized Management Dashboard (VMD)
- Microsoft Virtual Server Migration Toolkit (VSMT)
- Moka5 LivePC Engine
OpenVZ:
Tool Type: Server Platform
Developer/Sponsor: SWsoft
Available From:
This operating system-level virtualization platform, also called a 'containers-type' platform offers Linux users a simple and free way to create virtualized environments that operate like independent servers. OpenVZ proponents claim the platform offers less of a performance hit than solutions such as VMware and Xen.
FreeVPS:
Tool Type: Server Platform
Developer/Sponsor: Positive Software
Available From:
Another Linux-based solution, FreeVPS enables users to create isolated virtual private servers that are independent from one another and from hardware. Free VPS also offers shared administration for data backups, task and network traffic monitoring and batch installations.
SunxVM:
Tool Type: Platform and Management Console
Developer/Sponsor: Sun Microsystems
Available From:
The open source xVM hypervisor is based on the Xen hypervisor but is based on Sun's Solaris kernel rather than Linux. Sun also offers free distributions xVM Ops Center, which is designed to simplify administration of virtualized servers. These solutions are free, but support will cost you in the form of a subscription.
PlateSpin Power Recon:
Tool Type: VM Inventory
Developer/Sponsor: PlateSpin
Available From:
This solution is offered free for up to 100 servers. It gives users the power to create a software and hardware inventory for physical and virtual servers running on Windows, Linux and Solaris operating systems. This can be a great resource for asset management and also to plan for power and cooling needs.
VirtualBox:
Tool Type: Server/Desktop Platform
Developer/Sponsor: innotek
Available From:
This x86 virtualization solution is open source, but also comes with a software development kit to allow for easy interface customization. The VMs created by VirtualBox have their settings stored in XML, allowing for hardware independence and easy transfer.
Vizioncore vOptimizer Free Ware:
Tool Type: Performance Optimizer
Developer/Sponsor: Vizioncore
Available From:
This free version of Vizioncore's vOptimizer allows a maximum of two users to reduce their virtual machine's hard drive to the most compact size possible and tweaks Windows guest operating systems to improve speed and performance.
Virtual Iron Single Server Edition:
Tool Type: Server Platform
Developer/Sponsor: Virtual Iron
Available From:
This is Virtual Iron's most basic offering, a free edition for single servers that allows the creation of up to 12 virtual machines on local storage. It is usable for Windows or Linux operating systems and can be a good solution for items like file and print servers.
Enomalism Virtualized Management Dashboard (VMD):
Tool Type: Management Dashboard
Developer/Sponsor: Enomaly Inc
Available From:
This web-based virtual server manager can be a key utility for organizations that have already embraced virtualization and are now trying to get a handle on their environment. The dashboard can assist with load balancing, configuration management, capacity diagnosis, deployment planning and automatic virtual machine migration.
Microsoft Virtual Server Migration Toolkit (VSMT):
Tool Type: Migration Tool
Developer/Sponsor: Microsoft
Available From:
This free utility from Microsoft enables administrators to easily transfer a physical server into the virtual realm. It is limited to migrations into Virtual Server 2005, but can be very useful in automating migrations within this environment.
Moka5 LivePC Engine:
Tool Type: Desktop Platform
Developer/Sponsor: Moka5
Available From:
This desktop virtualization platform allows you to create a virtual machine that can be launched from a USB device, which can be ideal for testing applications in a virtualized environment without virtualizing the whole system. Be aware, though, that it won't work in a system that has already been virtualized.
Conclusion:
Higher‐density virtual machine platforms make it possible to conserve space, maintain functionality, and keep your performance constant—while at the same time lower costs of management, cooling, and power. TCO benefits make it possible to create an environment with smaller computing footprints while losing nothing in the transition.