№4(15)(2013)

Virtualization in computer systems is a term that can be attributed to different methods, techniques and approaches to create virtual (rather than actual) version of something, for example, virtual hardware platforms, operating systems, storage device or network resources. In recent years, virtualization is gaining popularity and is now an integral part of many systems and processes used in everyday life.

The concept of virtualization can be divided into two basic areas:

virtualization platforms - a product of this type of virtualization is virtual machines that run on real hardware and software systems;

Virtualization of resources - this type of virtualization aims to simplify presentation, or a combination of hardware resources for user, and, consequently, for software.

If we reject terminology and say in simple language, we can describe these directions as a separate hardware-software system for several virtual and otherwise, combining several hardware or hardware and software into a single virtual set. Let us consider each of these areas separately, to see where we are already using virtualization technology and where it would be appropriate to apply.

Virtualization platform refers to creation of software systems on existing hardware and software systems, which are dependent or independent from these complexes. With such virtualization, the system that provides hardware and software resources, is called the host, and simulated systems - the guest. Virtualization can be multilevel. The first thing that can be identified is a complete emulation. In this emulation platform guest uses all resources of the host, while remaining unchanged. This type of emulation you can emulate different hardware architecture without reference to the host. This approach was used in developing software for processors that have not come up for sale, as well as low-level operating system settings. This method has several drawbacks, namely a significant reduction in processing speed, which is almost impossible to use it, and use all the resources that can emulate only one system.

Then you can select partial emulation. In this case, the guest machine virtualizes hardware and software only necessary for launch to run it in isolation from the host. This approach is allowed for guest machines of the same architecture as the host. Accordingly, it allows one hardware-software complex emulating several virtual machines. This type of emulation is quite popular and is widely used, as compared with full emulation - has much higher speed. This type of emulation can be very useful for companies as it allows you to place multiple servers with different roles and critical services on single hardware system. Giving preference to this set, we can provide reliable systems - choosing the best equipment and protection of information as to protect one hardware system is much easier than systems of similar complexes, especially when it is extensive.

In addition, you can select the level of virtualization for applications. This type of virtualization is not like previous ones, which used virtual environments or virtual machines to provide isolation applications. This application is placed in a container with necessary elements for its operation: registry files, configuration files, user and system objects. The result is a program that does not require installation on similar system. When you move it to another platform, virtual environment solves the problem with operating system and other software. This mode of behavior is very similar to the programming language interpreter. No wonder the program on JAVA refer to this type of virtualization, and most modern client-bank is written on JAVA. What's in it for developers? Fact is that they are guaranteed to be the same result on different platforms with the same initial data. Support for multiple platforms performs the developer of virtual machines - in this case - the corporation Oracle.

What kind of business can benefit by using virtualization platforms? First, server consolidation - moving services or roles of individual servers to virtual machines deployed on a hardware system for higher reliability of quality. This will save on hardware and refuse to provide greater stability. Also, change hardware settings of virtual machines is much easier to do, it's only an option in program, rather than separately attached hard disk or plate of RAM. Then we get a much better possibility of backup vehicles - it is simply a file or folder with files and copying them is many times easier than doing snapshots from third-party software during system downtime.

Among disadvantages of these steps of virtualization platforms are the fact that failure of hardware system will break down all virtual machines simultaneously, not one of the 20 (of course, if you are 20 of them), and all 20 at once. Of course, there will be a lot of effort transferring files from operating systems on different hardware system and expand work, but you need a spare system or quickly repaired broken. If company is a full-time software developers and they need to test on different systems or even on different devices (eg, tablets or phones), so that they do not buy and do not install on some computers, it is enough to use a virtual machine with established necessary operating system emulators or individual devices.

We turn to the second trend - virtualization resources. This virtual systems that enable focus, abstract and simplify management of resources groups such as network, data files, and namespaces. Types of this area are: association, aggregation and concentration of components. This type of virtualization means combining multiple physical or logical entity in group of resources with user friendly interface. These include:

• Multiprocessor systems that we face as one powerful (supports many processing abilities is now in almost all modern operating systems)

• RAID-arrays - combining multiple physical or logical media in a logical, to provide greater stability to refuse or improve processing speed, depending on configuration.

• Virtualization of storage used in construction of storage area network SAN (StorageAreaNetwork). This technology enables users or applications to address the data set by one name, while individual data can be stored on different resources in network.

• Virtual Private Network (VPN), and Network Address Translation (NAT), allowing you to create virtual spaces of network addresses and names.

Clustering of computers and distributed computing. This type of virtualization involves techniques that allow you combining multiple individual computers in a global system that together solve a common problem. Through clustering can be significantly improved bounce-resistance roles, services or any systems that are involved in it. Also, this kind of virtualization is sometimes used by criminals in association infected computers in a network to perform some actions.

Significant spread of virtualization is beyond doubt, so you need to be aware of cases and use the best achievements in development of computer technology. Virtualization is not a panacea, but it does not mean it is worse - on the contrary, with help of some points because it solved many times faster, cheaper, safer, and easier. Today, market presented a number of companies providing assistance when moving real systems on virtual platforms, but this is only a single aspect of virtualization. The very same idea is inherent in virtualization, finds increasing support as the simple process control - one of its main objectives, and about financial or any other benefits to speak in each case.