What is the best rate for the site? What is the difference between VDS and VPS? What is Shared, KVM and Virtualization? These and many other questions inevitably arise before any novice webmaster, and unfamiliar terms and mysterious abbreviations only exacerbate the situation, confusing even more. This material is intended to help understand the features of the services offered by hosting providers.
Types of modern hosting
Today, there are three main options for hosting web resources: dedicated, shared and VDS / VPS. Each of them has its own specific features and distinctive features.
- Dedicated Server is a type of hosting, in which a dedicated physical server is provided for the use of the client. Its owner gets full administrative access to the machine, can install any operating systems, including non-standard distributive assemblies, and also has the ability to make changes to the BIOS settings. As a rule, dedicated servers are used to deploy complex projects (for example, corporate portals with back-office functions for employees), cloud services, and high-performance business applications.
- Shared hosting involves placing a large number of sites within a single hardware and software platform. In other words, a single physical server provides dozens and hundreds of independent sites. Being the cheapest, it is ideal for start-up projects and sites with low attendance (business cards, portfolio), but it also has some limitations. Unlike VPS / VDS, users of shared tariffs do not have the ability to change software settings (as a rule, it is limited only by htaccess directives), add specific libraries or modify the kernel of the operating system. In addition, server resources are evenly distributed among all participants, which can lead to a serious decrease in performance.
- VDS / VPS is a service in which each hosting client receives its own virtual machine at its disposal, which is managed in exactly the same way as working with a physical one. The presence of root-access (provides super-administrator rights) allows you to make almost any changes to the settings and the composition of the existing software. At the same time, the cost of a virtual server VPS is significantly lower than the lease of the dedicated one, which makes it an ideal transitional option for dynamically developing projects and hosting applications that have specific requirements for the software environment.
Of all the listed services, VDS / VPS is clearly distinguished – only it is described by a double abbreviation. Many do not attach any importance to this; nevertheless, there is a difference, even if not so significant for most users.
VPS and OpenVZ
Assimilation of IT-terms in the Russian language often takes on bizarre forms. So, in Russia, web design (in the original designates the entire set of works on creating websites) in Russia began to be called exclusively the elaboration of the visual part of Internet sites. A similar situation occurred with the VPS / VDS (Virtual Private / Dedicated Server – Virtual Private / Dedicated Server).
If in the West, these abbreviations are synonymous and do not have a clear semantic distinction, then in the Runet, each of them was assigned to a specific technology. Traditionally, VPS is OpenVZ, and VDS is associated with KVM (Kernel-based Virtual Machine). Thus, in order to understand the differences between VPS and VDS, it is necessary to understand the features of virtualization methods. Consider each of the two main solutions separately.
OpenVZ is implemented at the operating system level, that is, all virtual machines are based on a single modified Linux kernel. Each of them is a separate server (VPS) with administrative access, but the features of the technology impose certain limits:
- the choice of distributions is limited exclusively to Linux;
- The only valid file system is ext4;
- there is no possibility of modifying the kernel, which excludes the launch of a number of non-standard modules (OpenVPN, PPTP, IPSEC and others);
- management of the network screen and running processes is limited (depends on the settings of the root operating system);
- low privacy: the OS administrator has full access to all hosted on the VPS server .
In the case of KVM, virtualization is carried out by the hypervisor, a specialized program that is a virtual machine manager. It provides each container with access to existing hardware resources and ensures their functioning. Unlike OpenVZ, KVM provides a much larger range of possibilities, thanks to which VDS can serve as a full-fledged replacement for a dedicated server:
- work with any operating system, including Windows, FreeBSD and non-standard assemblies;
- the ability to format disk space under any existing file system;
- server management in the early stages of boot (including the BIOS screen) using the RFB protocol;
- full access to sockets, processes, as well as the possibility of modifying the OS kernel;
- high degree of privacy: only the owner has direct access to the contents of each container.
These differences play a role only if the virtual server is planned to be used to host specific applications. Most users are interested in the difference between VDS and VPS in terms of performance, scalability and reliability. This really has a place to be.
The OpenVZ technology assumes the dynamic distribution of available resources among all machines. Its main advantage is the ability to change the limits of allocated capacity without rebooting, literally in a couple of clicks. At the same time, this approach leads to dependence on the “neighbors” in the server. Excessive load on one VPS can lead to a decrease in the performance of the entire cluster.
In turn, when using KVM, this situation is completely excluded. Each VDS receives a strictly defined amount of computing resources and under no circumstances can go beyond them. At the same time, KVM is distinguished by the highest reliability comparable to the fault tolerance of physical machines. The only drawback is much less flexibility: if parameters such as the amount of RAM and CPU can be changed after a reboot, then changing the size of the disk space in some cases is simply impossible.