Virtuozzo is a software application for enterprise server virtualization that allows an administrator to create virtual environments on a host computer at the operating system (OS) layer.

Instead of having one physical machine run muliple operating systems simultaneously, as the virtual machine model used by VMware and Mircrosoft Virtual Server or XEN does, Virtuozzo approaches virtualization by running a single OS kernel as its core and exporting that core functionality to various partitions on the host. Each of the partitions effectively becomes a stand-alone entity called a virtual private server (VPS).

Virtuozzo comes with a proprietary Kernel Service Abstraction Layer (KSAL) that manages access to the kernel and prevents any single VPS from bringing the entire physical server down. It also has a proprietary file system to completely isolate the partitions, a security precaution that prevents a software fault in one partition from impacting an application or data in another partition.

Every VPS has its own network address and its own set of login credentials, system processes and daemon services. Because the underlying operating system is always running, each VPS can be rebooted independently and data can be migrated from one virtual environment to another on a live host. This capacity — which is not possible with the virtual machine model — is one reason why Virtuozzo has the reputation for being a good choice for production servers working with live data and applications.

Virtuozzo’s architecture eliminates system calls between layers, which reduces CPU usage overhead dramatically. Common binaries and libraries on the same host machine can be shared, making it possible for administrators to put literally thousands of VPSs on the same machine, each functioning as a stand-alone server.

Administrators using Virtuozzo have three management options: the command line, Virtual Management Center (a GUI interface for management and monitoring) and Virtual Control Center (a Web-based interface for remote access).

Virtuozzo is created and distributed by SWSoft. In 2006, SWsoft released the core of Virtuozzo under the GNU GPL (General Public License) in an open-source project called OpenVZ.

Advantages of a Virtual Private Server (VPS)

Virtual Private Server (VPS) gives you the features and functions of a fully managed dedicated web server but without the price of a dedicated server. You have full control of your Virtual Private Server (VPS) including full root ssh/rdp access to install your own customize software or applications not viable on a linux or windows shared hosting environment. Since a Virtual Private Server (VPS) is an isolated web hosting environment
it allows you more freedom to install and run complex scripts that aren’t allowed on a linux windows shared web hosting environment such as sending out a mailing list and since you get your own mail server you don’t have to worry about other users blacklisting the mail server ip, it allows you to create reseller hosting accounts if you are a reseller, and more.

With VPS Hosting you get dedicated amount of resources, full root access, privacy and isolation, ability to install third party software on the vps, remote reboot etc. Virtual Private Server (VPS) hosting plans give you room to expand before you have to invest in a full fledged dedicated server.

Disadvantages of a Virtual Private Server (VPS)

One of the many drawbacks of Virtual Private Server (VPS) is the problems related to vps maintenance. The virtual private servers have their own Operating system and software. The physical web server will have to look after all these operating systems without any fail. The control panel will have to make sure that the servers are delivering high performance with a superior up time. And the host needs to make sure that security and
updates are offered without any issues.

VPS Hosting

Virtual Private Servers or Virtual Dedicated Server or VPS Hosting bridge the gap between simple shared hosting/linux windows shared hosting and a dedicated server hosting solution. You’ll get all of the benefits of a dedicated web server without the worry. Have a problem? You still have customer support from your VPS hosting account host to come to the rescue should you need it.

VPS Hosting behaves exactly like a dedicated server. Amazingly, virtual private servers provide all of the following:

* Each VPS hosting account provides the account owner with dedicated processes, users, operating system, files, and provides full root access.
* Each VPS hosting account has its own IP addresses, port numbers, tables, filtering and routing rules.
* Each VPS hosting account can have its own configuration files for the system and app software. Ever need to edit php.ini? You can easily with your own virtual private server.
* Each VPS hosting account can have its own versions of system libraries or modify existing ones.
* Each VPS hosting account can delete, add, modify any file, including files in /root, and install its own application software or custom configure/modify root application software.

Managed and Unmanaged VPS Hosting

The unmanaged server hosting is suitable for small scale business. But the managed VPS hosting is most suiting for large scale business. They don’t have much time to spend on the smaller areas of hosting. So also they don’t want to spend extra money for that. So they opt to give the work of hosting their web site to a third party who will essentially manage the entire thing.

All the services are available at a fixed cost in managed VPS hosting. There is no separate cost for expert service and infra structure. The monthly rent will cover all work regarding the web site hosting. The result is that the pain of keeping track of the entire expense is reduced.

Apart from the web site hosting managed VPS hosting providers also provide services for private networks and data bases. SQL servers are also hosted by these VPS managed hosting providers. Users can enjoy a wide service that includes database management and load sharing from the VPS hosting servers.

The maintenance of equipments will be included under the service by the VPS hosting providers. The software services charge extra money from the part of the VPS hosting service providers. This will charge only a small amount from the part of the users. Thus the companies can get the entire thing managed by the providers for them.

The managed hosting services help you in the way that you don’t have to suffer any headache of managing the web site hosting. The efficiency will be increased many times if we are using a managed provider as they are skilled technicians. The cost needed to get all these things done will also be very small.

The choice of selection between a managed and an unmanaged VPS hosting provider is based on the skill of the user. The business also influences your selection. Small business can select unmanaged VPS hosting whereas large business can go for a managed VPS hosting.

Linux VPS Hosting : cPanel VPS Hosting

VPS hosting is made using the method of virtual private servers. The users are allowed to use a dedicated server by partitioning the physical server. The customers at each server will get all the resources and also a dedicated operating system. There are dedicated entities for all the servers connected to the main physical server. The end result is that there is total isolation and security in the VPS system.

There are different types of VPS hosting available. CPanel is a VPS hosting service provided to make the web administration a user friendly task for the clients. The graphics used in cPanel make the interface highly user friendly and the clients can manage the web site in a simple manner. The web site development and the management never remains a tough task for the end users with the help of this software.

Cpanel VPS hosting uses images and graphics for creation of lists and emails. This makes the handling of the web site tasks an easier job even for the novice user. In Cpanel, the applications and the script work hand in hand, thus hosting the site and designing the set up will be together coupled. This service package is easy to obtain and so the users readily go for it.

The users can easily access the disk space and bandwidth using cPanel. The main use of cPanel VPS hosting is found when web site is hosted for commercial and business purposes. The main uses of user friendly interface are therefore to manage the keys and to maintain mail accounts and mailing lists.

The software used for web hosting and the operating system acts separately. The software is updated and is always the latest version that is used, but at times up gradation becomes a difficult task. There are updates performed automatically.

Disadvantages of VPS hosting

VPS or virtual private servers are used to get multiple virtual servers from a single physical server. The method is implemented by portioning the real server. The resources and OS are allocated independently for the virtual servers. This allows for independent execution of the virtual servers on its own. The performance of one server never interferes with that of another virtual server connected to the same physical server.

But the advantages of the virtual servers are often over shadowed by many disadvantages faced by the system. One of the many drawbacks of virtual servers is the problems related to maintenance. The virtual servers have their own OS and software. The physical server will have to look after all these operating systems without any fail. The control panel will have to make sure that the servers are delivering high performance with a superior up time. And the host needs to make sure that security and updates are offered without any issues.

The virtual servers can be sitting idle for a long time. Their resources will be unused at such times. This leads to failure of making the proper use of the available resources. To avoid this, the physical servers may not provide the real resources to the virtual servers. All this requires proper handling of the working of the virtual environment which demands effort from the part of the host.

The virtual servers work with the help of the resources allocated to them by the physical server. A minimum number of resources will be allocated as there are instances of wastage of the resources by the virtual servers. So when the virtual server has to face a high rise in the traffic, it may not be able to meet the challenges for resources. This slows down the performance of that server and can even put it in a halt state by want of resource.

There can be too many virtual servers connected to a single physical server. The same computer will have to handle their requests and integrate them properly which might fail at times. If any server happens to use other resources, rendering the services in time will be blocked. Speed and performance will have to be compromised. Mismanagement can lead to degrading the virtual server as a whole. This will violate the security and isolation policies of virtual private servers.

These disadvantages can hinder the users from enjoying the benefits of virtual private servers properly. But the advantages are so great and brilliant that, end user often forgets the negatives and prefer to go for VPS in their business. The ultimate aim is making profit from little investment which is highly possible through VPS. The benefits supplemented with the profit have always been the reason for the success of VPS.

Linux VPS Hosting

VPS or Virtual private servers are used to get multiple servers from a single physical server. The virtual private servers are fully independent with their own dedicated resources and operating system. They function completely independent of one another and so the performance problem faced by one server will never affect another server.

VPS is mainly used in web hosting services. They are highly useful for commercial web hosting as it is very less expensive. The web hosting companies can easily give each of its clients a dedicated server. These servers are not physically bought and so they are very cheap. VPS has the flexibility that it can go with any architecture like Linux or windows or mainframe. This is mainly made use of in Linux web hosting services using VPS.

Linux is highly useful in that it offers a wide range of services for the end users. The web site hosting will be easier with Linux by virtue of the free services that Linux offers for hosting and running the web site. Linux can be combined to work with other systems in a simple manner to get added benefits.

Linux can join with Apache and PHP. This will bring about new methods in all the three together to get a better structure and format for web sites. A closer research will show that it is this attractive format that helped in the designing of most highly visited web sites in the internet.

Linux is preferred to windows because PHP can work better in collaboration with a Linux server as compared to a windows server. This is easily identified when the PHP scripts are loaded and find it difficult to handle in windows. Otherwise the difference is negligible. But when the heavy load is not suitable to work in a windows environment, Linux will prove to be the best partner for PHP.

There are many advantages of using VPS. Some examples of the advantages include:

* Provision servers in minutes

* Migrate VPSs in the time of network data transfer, nearly eliminating planned downtime and enabling fast reaction to unplanned downtime situations

* Monitor OS and application software versions and update/upgrade easily across servers and virtual servers

* Maintain corporate SLAs

* Automate routine tasks such as upgrades and updates

* Reduce the number of required physical servers and corresponding support

* Minimize software license and support requirements

* Increase server utilization and maximize server potential

Virtual Private Servers are feature rich and functionally equivalent to a Dedicated server. Also referred to as a Virtual Dedicated Server, a VPS (Virtual Private Server) empowers you with the flexibility and freedom of a dedicated server at a fraction of the cost.

• You have your own IP Address.
• Root access.
• Complete control over your file system and environment.
• Dedicated/Guaranteed CPU, Memory, Disk Space and Networking.

Virtual Private Server (VPS) Benefits

* Outstanding Multi-Homed Network
* Complete System Isolation
* Dedicated resources (CPU, RAM, Disk space)
* Host Unlimited Domains
* Running the stable Linux OS
* cPanel/WHM and Plesk control panel license for easy management
* Fantastico
* Dedicated IP Address(es)
* Install custom softwares and applications
* Independent Servers and Services: Apache/IIS6, FTP, SMTP, BIND, Databases, etc…
* Full Root/Administrator Access
* Choice of OS (Linux VPS)
* Windows 2003 Server (Windows VPS) with Full support for ASP .NET 2.0, MS SQL Server 2005
* Connect directly using SSH, Remote Desktop or Terminal Services
* Install/Uninstall Programs or Services (.exe’s)
* Customize your Server Software
* Database Support
* Superior Uptime
* Powerful and Secure Server Technology
* Protected by Enterprise Firewall/Intrusion Prevention appliances

Functions of a Linux Virtual Private Server (VPS)

. Add/Delete/enable/disable/restart VPSs
. Schedule Backups
. Rebuild VPSs using a different template
. Reset Root Password
. File Manager
. Integrated Java applet based SSH client
. Backup/Restore VPSs
. Manage IP addresses for each VPS
. Command Center, which allows you to execute arbitrary commands in the VPS and view the output