Why do I need server virtualization?

Recently, users are increasingly hearing about such a concept as "virtualization". It is believed that its use is cool and modern. But far from every user clearly understands what virtualization is in general and in particular. Let's try to shed some light on this question and we will touch upon the server virtualization systems. Today, these technologies are the foremost, because they have many advantages in terms of security and in terms of administration.

What is virtualization?

Let's start with the simplest - the definition of a term describing virtualization as such. Let's note at once, that on the Internet it is possible to find and download any allowance on this question like a directory "Virtualization of the server for teapots" PDF-format. But when studying the material, an unprepared user may encounter a lot of confusing definitions. So let's try to clarify the essence of the issue, so to speak, on your fingers.

First of all, when considering the technology of server virtualization, let us dwell on the initial concept. What is virtualization? Following simple logic, it is not difficult to guess that this term describes the creation of some kind of emulator (similarity) of some physical or software component. In other words, it is an interactive (virtual) model that does not exist in reality. However, here are their nuances.

The main types of virtualization and the technologies used

The point is that in the concept of virtualization there are three main directions:

• representation;
• Applications;
• Servers.

For understanding, the simplest example can be the use of so-called terminal servers that provide users with their own computing resources. The user program is executed on the remote server, and the user sees only the result. This approach allows reducing the system requirements for a user terminal, the configuration of which is obsolete and can not cope with the given calculations.

For applications, such technologies are also used widely enough. For example, it could be virtualization of a 1C server. The essence of the process is that the program runs on one isolated server, and a large number of remote users get access to it. The software package is updated from a single source, not to mention the highest level of security for the entire system.

Finally, we mean the creation of an interactive computer environment, the server virtualization in which completely repeats the real configuration of the "iron" counterparts. What does this mean? Yes, that, by and large, on one computer you can create one or several additional ones that will work in real time, as if they existed in reality (server virtualization systems will be discussed in more detail later).

At the same time, it does not matter which operating system is installed on each such terminal. By and large, this does not have any effect on the main (host) OS and the virtual machine. This is similar to the interaction of computers with different OSes on the local network, but in this case virtual terminals may not be connected.

Choice of equipment

One of the obvious and undeniable advantages of virtual servers is the reduction of material costs for the creation of a fully functional software and hardware structure. For example, there are two programs that require 128 MB of RAM for normal operation, but they can not be installed on a single physical server. What should I do in this case? You can buy two separate servers for 128 MB and install them separately, and you can buy one with 128 MB of RAM, create two virtual servers on it and install two applications on them.

If anyone does not understand, in the second case, the use of RAM will be more rational, and the material costs are significantly lower than when buying two independent devices. But this is not the only thing.

Advantages in the security system

As a rule, the server structure itself implies the presence of several devices for performing certain tasks. In terms of security, system administrators install Active Directory domain controllers and Internet gateways on different servers rather than on one server.

In the case of an attempt to external intervention, the gateway is always subjected to the first attack. If the server is also installed with a domain controller, then it is very likely that AD databases will be damaged. In a situation with targeted actions, all these can be taken over by intruders. Yes, and recovering data from a backup copy is quite a troublesome task, although it takes relatively little time.

If we approach this issue from the other side, it can be noted that server virtualization allows you to bypass installation restrictions, and also quickly restore the desired configuration, because the backup is stored in the virtual machine itself. True, it is believed that the virtualization of servers with Windows Server (Hyper-V) in this view looks unreliable.

In addition, the issue of licensing remains controversial. For example, for Windows Server 2008 Standard there is only one virtual machine running, on Enterprise - four, and on Datacenter - in general an unlimited number (even copies).

Administration issues

The advantages of this approach, not to mention the security system and cost savings, even when virtualizing servers with Windows Server, should first of all be assessed by system administrators who are servicing these machines or local networks.

Very often a stumbling block is the creation of backup copies of the system. Usually when creating a backup, third-party software is required, and reading from an optical media or even from the Internet takes longer, compared to the speed of the disk subsystem. Cloning of the server and the virtual machine can be done in just a couple of clicks, and then quickly deploy a workable system even on "clean" hardware, after which it will work without failures.

In VMware vSphere, server virtualization allows you to create and save so-called snapshots of your virtual machine (snapshots), which are special images of its state at a certain point in time. They can be represented in a tree structure in the machine itself. Thus, it is much easier to restore the working capacity of a virtual machine. In this case, you can arbitrarily choose recovery points, rolling back the state, and then forward (Windows-systems can only dream of this).

Server Virtualization Software

If we talk about software, you can use a huge number of applications to create virtual machines. In the simplest case, you use the native tools of Windows-systems, with which you can make server virtualization (Hyper-V - built-in component).

However, this technology also has some drawbacks, so many prefer software packages like WMware, VirtualBox, QUEMI or even MS Virtual PC. Although the names of such applications vary, the principles of working with them are not particularly different (except in details and some nuances). With some versions of applications, virtualization of Linux servers can also be done, but these systems will not be considered in detail, since most of our users use Windows all the same.

Server virtualization on Windows: the simplest solution

Since the release of the seventh version of Windows, it has a built-in component called Hyper-V, which made it possible to create virtual machines using the system's own resources without using third-party software.

As with any other application of this level, the future virtual computer can be modeled in this package , specifying the size of the hard disk, the amount of RAM, the presence of optical drives, the desired characteristics of the graphic or audio chip - in general, all that is available in the hardware Conventional server terminal.

But here you need to pay attention to the inclusion of the module itself. Hyper-V servers can not be virtualized without first enabling this component on the Windows system itself.

In some cases, it may be necessary to activate the support of the appropriate technology in the BIOS.

Use of third-party software products

Nevertheless, even despite the means by which virtualization of Windows-system servers can be done, many experts consider this technology somewhat inefficient and even overly complicated. It is much easier to use a ready-made product in which similar actions are performed based on automatic selection of parameters, and the virtual machine has great capabilities and flexibility in management, configuration and use.

We are talking about the use of such software products as Oracle VirtualBox, VMware Workstation (VMware vSphere) and others. For example, a VMware virtualization server can be created in such a way that the analogues of computers made inside the virtual machine work separately (independently of each other). Such systems can be used in training processes, testing of any software, etc.

By the way, it can be separately noted that when testing software in a virtual machine environment, you can even use programs infected with viruses that will show their effect only in the guest system. On the main (host) OS this will not affect in any way.

As for the process of creating a computer inside the machine, in VMware vSphere server virtualization, as well as in Hyper-V, is performed on the basis of the "Wizard", however, if you compare this technology with Windows-based systems, the process itself looks somewhat easier, because the program itself Can offer some kind of templates or automatically calculate the necessary parameters of the future computer.

The main disadvantages of virtual servers

But, despite the many advantages that virtualization of the server gives to the same sysadmin or the end user, such programs have some significant drawbacks.

Firstly, you can not jump above your head. That is, the virtual machine will use the resources of the physical server (computer), and not in full, but in a strictly limited volume. Thus, for the virtual machine to work properly, the initial configuration of the hardware must be quite powerful. On the other hand, the purchase of one powerful server will still be much cheaper than buying several with a lower configuration.

Secondly, although it is believed that several servers can be integrated into a cluster, and if one of them fails, you can "move" to another one, in the same Hyper-V this can not be achieved. And it looks like an obvious minus in the issue of fault tolerance.

Thirdly, the question of transferring to a virtual space of resource-intensive DBMSs or systems like Mailbox Server, Exchange Server, etc. is obviously disputable. In this case, there will be obvious inhibition.

Fourthly, for the correct operation of such an infrastructure, you can not use only virtual components. In particular, this concerns domain controllers - at least one of them must necessarily be "iron" and initially available on the Web.

Finally, fifthly, virtualization of the server is fraught with another danger: the failure of the physical host and the host operating system will entail the automatic deactivation of all associated components. This is the so-called single point of failure.

Summary

Nevertheless, despite some shortcomings, the advantages of such technologies are clearly greater. If you look at the question of why you need server virtualization, here are a few key aspects:

• Reduction in the number of "iron" equipment;
• Reduction of heat generation and energy consumption;
• Reduction of material costs, including purchase of equipment, payment of electricity, purchase of licenses;
• Simplified maintenance and administration;
• The ability to "migrate" the OS and the servers themselves.

Actually, the benefits of using such a technology are much greater. Although it may seem that there are some serious shortcomings, with the correct organization of the entire infrastructure and the use of the necessary management tools for trouble-free operation in most cases, the emergence of such situations can be avoided.

Finally, for many, the choice of software and the practical implementation of virtualization remains open. But here it is better to turn to specialists for help, since in this case we were faced with the issue of general familiarization with server virtualization and the expediency of implementing the system as such.