First of all, let's be defined - as we shall name it? Efforts of the various companies, both software developers, and the companies offering this service, had been created some names as a matter of fact the same:

VPS - Virtual Private Server

VDS - Virtual Dedicated Server

DDS - Dynamic Dedicated Server

Actually the same also is often used by some companies for delimitation of various realizations and offers VPS.

Is a division of one physical server on independent from each other virtual a server. To divide it is possible both Unix, and Windows systems. In what all charm of it? As a result of such division are formed independent allocated a server, physically placed on one server.

• Everyone VPS has own distribution kit of operating system in which it has the rights of a level root (UID: 0) for Unix or Administrator for Windows, that allows to compile, establish own software with own configuration.
• Everyone VPS can have one or the several allocated IP through which entering and proceeding connections are carried out. Even if on one VPS there is DDOS an attack on next it is not reflected in any way (it is necessary to notice, that can be reflected, but for other reasons).
• The guaranteed minimal resources of a server. To you never will tell, that you spend more resources CPU or memory as it often happens on a usual virtual hosting.
• Fast reboot a virtual server, an opportunity of backup copying VPS of all system.
• Greater stability in work at lower cost.

• Non-standard configurations, the non-standard software are necessary to you or simply wish to have management of all server in the hands, but the allocated server is superfluous on resources.
• Your sites spend many resources of a server and HSP disagree to place them on a virtual hosting.
• The guaranteed resources are necessary to you.

• If you pay for VPS more, than for a virtual hosting it does not mean yet, that sites will work for you more quickly. Probably, as on the contrary, more slowly. All depends on resources which are allocated under yours VPS, and also them guaranted. Do not forget, that you will have copy OS, some services which will spend resources of the processor, will work for you memory and, probably, networks. Besides it is not necessary to forget, that else scripts of web-sites will work in the same place and actually.
• Do not forget, that you buy the dedicated server. And it means, that you should know even bases of work with operating system which is established on VPS. If you do not have necessary knowledge/times on it you have 2 variants - to find offers where administration VPS (most likely it is offered will be as in addition paid service) or to employ the external administrator. Also installation of one set of free-of-charge or paid control panels is possible, that essentially will help management. Will operate in this case a server easier, but the knowledge of system all the same is necessary.
• What actually you buy? Now in market VPS of services it is possible to find set of the various offers based on different technologies (the most popular are described below) which have different ways virtualizing and, accordingly, different final figures of the guaranteed resources, and different cost with a kind of the same resources. All this is aggravated still with that many resources are expressed by relative figures which directly depend on a configuration of a physical server.

How to make a correct choice? Some advice:

1. Find the information on the used technology. In this clause the information on all most popular technologies contains.

2. Learn a configuration of a server on which you will be placed VPS. Learn total placed VPS on such server. Depending on used technology of virtualizing, there there will be this or that percent of overselling. It means, that calculation that all VPS during one moment will not use a maximum of the guaranteed resources is done. If the technology with own kernel for everyone VPS (UML, Xen) in this case the percent of overselling should be minimal is used. If the technology with one kernel for all VPS (Virtuozzo, FreeVPS) overselling it is possible in enough big degree, but is recommended it is no more, than in 2 times on resources of memory and cpu. Technology Chroot BSD (VDSmanager) allows to do overselling in 10 times and more, that is in most cases justified and admissible.

3. Learn, whether will be limited, and how much, following key parameters: guaranteed CPU, guaranteed CPU in percentage of 100% CPU of a physical server, quantity of the accessible processes, the guaranteed mbytes of memory RAM, swap.

4. Will be an opportunity to make a painless upgrade? Under painless that data will be kept all is understood and will not be or there will be an insignificant break. The matter is that at large upgrades often it is necessary to transfer VPS on other physical server.

• Are VPS administered? Whether will be monitoring VPS is carried out? Whether the support HSP will eliminate malfunctions on VPS, is free-of-charge or for separate cost?
• More often at order VPS to you will free of charge put minimal installation OS and the basic, most popular and necessary packages necessary for work with web by sites, such as web-server Apache, dns-server BIND, MySQL and others, and also support of programming languages, for example, php. Nevertheless, to you, probably, will put only naked OS, and the rest will suggest to put independently.
• It is important, how many IP you receive also what. Rules of some national zones demand, that IP a DNS-server were from different C classes network. If you wish to use on the VPS own NS and wish to place there domains .ru, .su, .de and some other you need to have a minimum 2 IP from different C classes network.