Virtualization NIIT WHITE PAPER SEPTEMBER 2011

Transcription

1 Virtualization WHITE PAPER SEPTEMBER 2011

2 National Institute of Information Technologies White Paper On VIRTUALIZATION Submitted by: Mohsen Shahbazi Behzadi Student ID: S Date: 28 Sep 2011 Esfahan Iran

3 TABLE OF CONTENTS 1) Introduction...P.1 2) A Short Look at Virtualization History...P.1 3) Virtualization Benefits...P.2 4) The Different Types of Virtualization...P.3 a) Hardware assisted Virtualization(Platform)...P.3 b) Server Virtualization...P.3 i) Full Virtualization...P.4 ii) Para Virtualization(VPM)...P.4 c) OS-level Virtualization(Operating System level)...p.5 d) Application Virtualization...P.6 i) Desktop Virtualization...P.6 e) Network Virtualization...P.7 f) Storage Virtualization...P.8 5) The Reasons to Adopt Virtualization strategies...p.8 6) The Challenges of Managing a Virtual Environment...P.9 a) Policy-based management...p.9 b) Bandwidth implications...p.10 c) Image proliferation...p.10 d) Security...P.10 e) Human issues...p10 7) References...P.10 Overview Virtualization is a technology that enables running multiple operating systems side-by-side on the same processing hardware. This white paper provides an easy to understand introduction to virtualization, and explains the benefits that virtualization technology can provide for engineering applications.

4 Introduction Virtualization is a technical innovation, designed to increase the level of system abstraction and enable IT users to harness ever-increasing levels of computer performance. At its simplest level, virtualization allows you, virtually and Cost-effectively, to have two or more virtual computing environments, running different operating systems and applications on one piece of hardware. For example, with virtualization, you can have both a Linux virtual machine and a Microsoft Windows virtual machine on one system. Alternatively, you could host a Microsoft Windows 95 desktop and a Microsoft Windows XP desktop on one workstation. In slightly more technical terms, virtualization essentially decouples users, operating systems, and applications from the specific hardware characteristics of the systems they use to perform computational tasks. This technology promises to usher in an entirely new wave of hardware and software innovation. For example, and among other benefits, virtualization is designed to simplify system upgrades (and in some cases may eliminate the need for such upgrades), by allowing users to capture the state of a virtual machine (VM) and then transport that state in its entirety from an old to a new host system. Virtualization is also designed to enable a generation of more energy-efficient computing. Processor, memory, and storage resources that today must be delivered in fixed amounts determined by real hardware system configurations will be delivered with finer granularity via dynamically tuned VMs. For example, consider a common engineering application that can benefit from virtualization (Running multiple operating systems in parallel).today, many designers need to take advantage of real-time processing or control while providing a graphical user interface. While traditionally this would have required two physical computers (One for each operating system), virtualization enables running both operating systems on the same PC or embedded controller. Eliminating the need for an extra computer means a better integrated overall system, a saving in cost, and a reduction in footprint. It is important to note that virtualization is not only being used in the engineering domain. Many information technology (IT) companies have used virtualization to consolidate large groups of servers at saving that can reach millions of dollars. This white paper will specifically outline the major benefits that virtualization can provide engineers, and provide an introduction to the types of (common) virtualization. A Short Look at Virtualization History When you think of the beginning of Server Virtualization, companies like VMW are may come to mind. The thing you may not realize is Server Virtualization actually started back in the early 1960 s and was pioneered by companies like General Electric (GE), Bell Labs, and International Business Machines (IBM). In the Early 1960 s IBM had a wide range of systems; each generation of which was substantially different from the previous. This made it difficult for customers to keep up with the changes and requirements of each new system. Also, computers could only do one thing at a time. If you had two tasks to accomplish, you had to run the processes in batches. This Batch processing requirement wasn t too big of a deal to IBM since most of their users were in the Scientific Community and up until this time Batch processing seemed to have met the customer s needs. Because of the wide range of hardware requirements, IBM began work on the S/360 mainframe system designed as a broad replacement for many of their other systems; and designed to maintain backwards compatibility. When the system was first designed, it was meant to be a single user system to run Batch Jobs. The main advantages of using virtual machines with a Page 1

5 time sharing operating system was more efficient use of the system since virtual machines were able to share the overall resources of the mainframe, instead of having the resources split equally between all users. There was better security since each users was running in a completely separate operating system. And it was more reliable since no one user could crash the entire system; only their own operating system. Virtualization Benefits Save Hardware Cost and footprint Virtualization provides the ability to take advantage of multiple operating systems on one physical PC or embedded controller, without investing in a separate computer for every OS. This allows engineers to buy less hardware and reduce overall system footprint (Which is especially important in deployed applications). Take Advantage of Operating System Services With virtualization it is possible to take advantage of the capabilities offered by different operating systems on just one set of hardware. For example, a designer may wish to use graphics services provided by Windows in conjunction with deterministic processing provided by a real-time OS such as labview Real-Time. Make Use of Multicore Processors Virtualization software can allow users to directly assign groups of processor cores to individual operating systems. For example, if an engineer wishes to use Linux and a real-time OS, more CPU and memory resources can be allocated to the real time-time OS to optimize performance. Running virtualization software on a given computer allows designers to make the most of their processing resources by keeping processor cores busy. Increase System Security Since individual operating systems running on a virtualized machine can be isolated from each other, virtualization is one way to create secure machines. This reduces the need for multiple physical computers that operate at different security levels but are not fully utilized. Business Continuity and Disaster Recovery Virtualization allows easier software migration, including system backup and recovery, which makes it extremely valuable as a Disaster Recovery (DR) or Business Continuity Planning (BCP) solution. Virtualization can duplicate critical servers, so IT does not need to maintain expensive physical duplicates of every piece of hardware for DR purposes. DR systems can even run on dissimilar hardware. In addition, virtualization reduces downtime for maintenance, as a virtual image can be migrated from one physical device to another to maintain availability while maintenance is performed on the original physical server. This applies equally to Page 2

6 servers and desktops, or even mobile devices virtualization allows workers to remain productive and get back online faster when their hardware fails. The Types of Virtualization Hardware Assisted Virtualization 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. 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 operating system 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. Whether this is a problem depends on what type of applications they are running: the system is better suited to activities such as web browsing and word processing than activities such as video editing which eat up more processor power. Server Virtualization Server virtualization, also known as a Virtual Dedicated Server (VDS) or Virtual Private Server (VPS), is cheaper than a dedicated server and solves the resource-sharing problems of a shared server by earmarking resources for each subscriber and allowing each virtual server to run completely separately from the others, even running separate operating systems, if desired. Server virtualization also has applications within organizations, as it can allow tasks and processes that are not compatible to be operated on the same server completely without interaction or overlap, Page 3

7 making the use of the server more efficient. Another benefit of virtual servers is allowing for redundancy within a single piece of hardware. A second virtual server could contain the sample application and/or the same data to use as a backup in case of a failure. Server virtualization can be accomplished in three different ways. The first is referred to as full virtualization or the virtual machine model; the second as paravirtualization or the paravirtual machine (PVM) model; and the third is called OS-level virtualization or virtualization at the OS (operating system) level. Full Virtualization Full virtualization is a process where an entire computer system is made into a software construct. This construct acts like the original hardware in every way. Software that is designed for the hardware will install on the construct as though it was the actual computer and then run with little to no slowdown. Using full virtualization has several uses, such as testing software in a virtual environment or expanding the usefulness of a single computer or server through virtual operating systems. While partial virtualization is very common, full virtualization is relatively rare. In order to be full virtualization, an entire hardware system needs to be transformed into software. Every action and nuance of the original hardware needs to move over to the virtual system. Since this is such a large undertaking, and some system manufacturers take steps to discourage it, full virtualization is somewhat rare. It is much more common to find partial virtualization, where all the necessary system bits are present, but the physical hardware system handles much of the low-level calculations and functions. Paravirtualization Paravirtualization is a method of allowing software running on a virtual system to bypass the virtual interface and run operations on the system s actual hardware. In a standard virtual system, the only program that utilizes the system s actual hardware is the virtual interface. The rest of the software runs totally inside the virtual environment. With paravirtualization, there are ways that the included software can access actual resources rather than virtual ones. This speeds up certain functions without sacrificing computing power. In most virtual systems, a real machine has a program installed that operates as the virtual interface for the rest of the operations. This interface, often called a hypervisor, is usually inaccessible to the users of the virtual system; only people with actual hardware access can get to it. When virtual users do have access to the hypervisor, they are often severely limited in what they can do to the system. The hypervisor is essentially the center of the virtual system. It Page 4

8 oversees the installed virtual software and provides a platform for virtual users. When programs on the virtual system need access to hardware, the hypervisor will take the information and process it itself or format it and send it to the underlying system. In a system that uses paravirtualization, a virtual program has the option to bypass the virtual operating system and operate directly with the system s hardware when it needs hardware access. Some operations are very difficult for the virtual system to accomplish. When a virtual program needs to perform one of these tasks, it takes fewer resources for the program to skip the virtual layer and go directly to the hardware system. Paravirtualization is still done sparingly, as too many direct hardware calls can overtax the system. In order to use paravirtualization, both the actual system and the virtual system need certain preparations. The biggest factor is the paravirtualization software itself; only operating systems and hypervisors with paravirtualization capacity can perform these functions. While these are often excluded from a standard install, most server software companies have add-ons available that will give their products the correct capabilities. Virtualization at the OS (operating system) level Operating system virtualization is a method of altering a standard operating system so it may handle multiple users all at the same time. These individual users would not have any interaction with one another. Their information would also remain separate, even though they are using the same system. While this technology has several uses, the most common uses are in hosting situations and server consolidation. With operating system virtualization, a single system is set up to operate like several individual systems. The virtualized system is set up to simultaneously except commands from different users. These commands remain separate from one another; the results and impact of any given command has no effect on commands from others. This division of resources should be transparent to the user, they shouldn t be able to tell whether they are on a virtual system or not. A common example of this process is the logout command. On a normal computer system, logging out of the operating system will suspend user input until required by the logout system or the user logs back in. In a system using operating system virtualization, when one user logs out the operating system just logs out the single user, but the rest of the users are unaffected. There are two common circumstances where operating system virtualization is used, hosting environments and server consolidation. Web hosting companies, storage systems and other account-based hosting systems, often use virtual systems. Since the users of these types of systems require very few resources it is possible for many people to log on at once without taxing the system. Each user operates inside their own environment without interacting with, or seeing the resources of, other users. Page 5

9 The second common area where a user may encounter operating system virtualization is on a consolidated server. As computer systems increase in power, one new server may be able to take the jobs of several older ones. In this case, it is possible to combine all the server resources onto the new machine. Since the old servers were separate, it is often necessary to maintain the isolation used by the original systems. In both of these areas, multiple users that have no relationship to one another have to use the same server. This is one of the most common aspects of operating system virtualization. If the users were part of the same group, then they could coexist and share resources. The only reason to keep them separate is when the users have no relationship with one another and have no reason to combine systems. Application Virtualization Application virtualization is a process for changing the way that software runs on a computer s operating system. With application virtualization tools, software makers can create programs that will run on a wider range of operating systems, or in more diverse conditions. Making applications virtual helps to provide more compatibility for a piece of software in complex and diverse hardware setups. In traditional software design, a software program is executed by the operating system directly. With application virtualization, the process is different. The run-time process involves indirect program execution. This means that some remote technology or extra component is helping the computer to read and run the program. Different kinds of application virtualization include application streaming and desktop virtualization. In desktop virtualization, there may be helper elements installed to assist in the execution of software. In application streaming, help can be delivered through networks, over an Internet connection. Application virtualization is similar to what s called software as a service. Many software as a service or SaaS setups include applications training or similar methods. The overall benefit of SaaS is to provide software over the Web as opposed to selling it out of the box. In traditional out of the box setups, the user has to install and register a software product. With SaaS and application virtualization technologies, none of this is required. Desktop Virtualization Desktop virtualization is a computer process where individual workstations use a central desktop stored on a separate server. This server may have multiple desktop systems for different types of workers, such as a marketing department having a different desktop than tech support, but it doesn t have individual desktops for each worker. With a desktop virtualization process, a central system stores all of the system s information. This central server contains the hosted operating Page 6

10 system and configuration information. If the server hosts multiple desktops, it has a different configuration setup or operating system installed for each one. Generally, these desktops are very basic. They contain little by way of extra programming or personalized features. Many remote desktop systems allow individuals to save their personal settings on the server along with their desktop. These individual configuration files are usually very basic as well; the majority of systems try to keep desktops as similar as possible. Saving configuration settings is just the tip of what the server does in a typical desktop virtualization process. They also allow the saving of documents and web histories. This will keep all of the information generated by a workforce in a single, central, location. With the exception of the client side system that allows a person to access the desktops, everything is done completely on the desktop server. Network Virtualization Network virtualization is a method used to combine computer network resources into a single platform, known as a virtual network. It is achieved by software and services that allow the sharing of storage, bandwidth, applications, and other network resources. The technology utilizes a method similar to the virtualization process used to simulate virtual machines within physical computers. A virtual network treats all hardware and software in the network as a single collection of resources, which can be accessed regardless of physical boundaries. In simple terms, network virtualization allows each authorized user to share network resources from a single computer. There are two forms of network virtualization, external and internal. External virtualization generally combines multiple networks or parts of networks into a single virtual entity. Internal virtualization provides system-wide sharing and other network functionality to the software containers, which act as hosting environments for the software components of the network, on a single physical system. The external variety is the most commonly used method to create virtual networks. Vendors that distribute these virtualization tools generally offer either one form or another. Network virtualization is not an entirely a new concept. In fact, virtual private networks (VPNs) have been widely used by network administrators for years. Virtual local area networks (VLANs) also represent a common variation of network virtualization. Both serve as examples of how significant advancements in computer connectivity methods have made it possible for networks to no longer be restricted by geographical lines. Page 7

11 Storage virtualization Computer data is stored on disks and solid state media for availability over days, months or years. In small systems, such as a personal computer there is a CPU and one or two hard disks. When a disk fails or runs out of space another disk has to be manually added, and, the data has to be placed on that disk. In large systems, there can be hundreds of disks and digital storage systems, and the complexity of managing the information increases considerably. Storage virtualization is the grouping of storage devices such that it seamlessly appears to be one large storage device. Storage virtualization can be handled by hardware or software, or a combination of the two. It has a number of benefits. Data may be moved from one device to another device behind the scenes while the system is making requests, and the request is automatically routed to the new location. When a storage device has to be added or removed, this can be done without bringing down the system. This increases the availability of the system to the ultimate users. With storage virtualization, information can be intelligently managed; for example, data that is accessed less frequently can be moved to a slower device. Utilization of storage space could be improved. Each storage device by itself may have unused space, but that unused space might be too small to be utilized for a single file that the operating system wants to place. With storage virtualization, unused space on multiple devices is automatically accumulated because parts of the file can be stored on separate devices. Storage virtualization thus provides the system with the storage it needs without getting bogged down by the limitations of the individual devices. Of course, now, a significant amount of information has been virtualized. It is very important that this information is retained in a fail-proof manner, usually by storing it in multiple locations. The Reasons to Adopt Virtualization Strategies Virtualization is a technology that can benefit just about any business. Thousands of IT executive around the world use virtualization solutions to reduce IT costs while increasing the efficiency, utilization and flexibility of their existing computer hardware. Here are a few of the top benefits to developing your virtualization strategy: Server Consolidation and Optimization: Virtualization makes it possible to achieve significantly higher sever utilization by pooling common infrastructure resources and avoiding the need for one server for each application model. Infrastructure Cost Reduction: With virtualization, you can reduce the number of servers and related IT hardware in the data center. This leads to reductions in real estate, power and cooling requirements, resulting in significantly lower IT costs. Page 8

12 Improved Business Continuity: Eliminate planned downtime and recover quickly from unplanned outages with the ability to securely backup and migrating entire virtual environments with no interruption in service. Improved Desktop Manageability & Security: Deploy, manage and monitor secure desktop environments that end users can access locally or remotely, with or without a network connection, on almost any standard desktop, laptop or tablet The Challenges of Managing a Virtual Environment While virtualization offers a number of significant business benefits, it also introduces some new management challenges that must be considered and planned for by companies considering a virtualization strategy. The key management challenges for companies adopting virtualization include: Policy-based management Bandwidth implications Image proliferation Security Human issues Policy-Based Management Enterprises should look to deploy automated policy based management alongside their virtualization strategy. Resource management, for example, should include automated policy-based tools for disk allocation and usage, I/O rates, CPU usage, memory allocation and usage, and network I/O. Management tools need to be able to throttle resources in shared environments, to maintain service levels and response times appropriate to each virtual environment. Administrators should be able to set maximum limits, and allocate resources across virtual environments proportionally. Allocations need to have the capability to change dynamically to respond to peaks and troughs in load characteristics. Management tools will also be required to automate physical to virtual, virtual to virtual, and virtual to physical migration. Bandwidth Implications Enterprises should make sure they have the appropriate network bandwidth for their virtualization requirements. For example, instead of one server using a 100Mb Ethernet cable, now 10 or even 100 virtual servers must share the same physical pipe. While less of a problem within the datacenter or for communication between virtual servers running in a single machine, network bandwidth is a significant issue for application streaming and remote desktop virtualization. These technologies deliver quite substantial traffic to end users, in most cases significantly higher than is required for standard-installed desktop computing. Streaming technologies, although in many cases more efficient than complete application delivery, also impose high bandwidth requirements. Page 9

13 Image Proliferation Operating system and server virtualization can lead to a rapid proliferation of system images, because it is so much easier and faster to deploy a new virtual image than to deploy a new physical server, without approval or hardware procurement. This can impose very high management and maintenance costs, and potentially lead to significant licensing issues including higher costs and compliance risks. This proliferation also leads to significant storage issues, such as competing I/O and extreme fragmentation, requiring much faster and multichannel disk access, and more maintenance time, effort, and cost. Enterprises need to manage their virtual environment with the same level of discipline as their physical infrastructure, using discovery tools to detect and prevent new systems from being created without following proper process. Security While virtualization can have many worthwhile security benefits, security also becomes more of a management issue in a virtualized environment. There will be more systems to secure, more points of entry, more holes to patch, and more interconnection points across virtual systems (where there is most likely no router or firewall), as well as across physical systems. Access to the host environment becomes more critical, as it will often allow access to multiple guest images and applications. Enterprises need to secure virtual images just as well as they secure physical systems. Human Issues Enterprises should not underestimate the potential for human issues to affect their virtualization plans adversely. Virtualization requires a new set of skills and methodologies, not just within IT, but often (certainly in the case of application and desktop virtualization) in the end-user community. Perhaps most importantly, this new technology requires new and creative thinking, not just new training and skills. Reference s Page 10