VPS Hosting Stuff

Following are examples of how to use your private server:

• Host a Web site, including an e–commerce site
• Support a corporate intranet
• Build a custom development environment
• Run Web–based calendaring
• Stream multimedia applications
• Host an online game forum
• Manage an email system
• Create a customer support tracking system
• Backup important data
• Host multiple Web sites

First, Linux (sometimes referred to as GNU/Linux or a Linux–based GNU system) is a UNIX–like operating system. Linux is distributed under the terms of the GNU General Public License (GPL) as published by the Free Software Foundation (FSF). Your private server account utilizes Red Hat Enterprise Linux (RHEL), a widely implemented corporate Linux standard. RHEL is based on open standards and is derived from the community–supported open source project called Fedora. The project is sponsored by Red Hat.

Then, a Virtual Private Server (VPS) is a hosting environment that gives you your own Linux virtual machine. Each private server provides a protected area that operates as an independent server. It enables you (and multiple customers) to share the expense of hardware and network connections and to eliminate the difficulty of maintaining them. Keep in mind that although multiple VPS customers share hardware, they do not share software. It has its own, complete directory structure, and set of dedicated application software. You can restart it without affecting any other private server accounts which share the same hardware.

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What is OpenVZ ?

OpenVZ is an open source container-based virtualization solution built on Linux. OpenVZ creates isolated, secure containers (otherwise known as VEs or VPSs) on a single physical server enabling better server utilization and ensuring that applications do not conflict. Each container performs and executes exactly like a stand-alone server; containers can be rebooted independently and have root access, users, IP addresses, memory, processes, files, applications, system libraries and configuration files.

Preparing Anything
1. Server With Centos 5 ( You can also choose other distro linux fedora, RHEL, etc ) in this tutorial we are using Centos 5 with 4 GB memory and 40 GB harddrive
2. Configure YUM to have a OpenVZ repository
3. Install OpenVZ Kernel
4. Configure Boot loader
5. Configure Sysctl
6. Disabled SELinux
7. Configure Conntracks
8. Installing OpenVZ utilities
9. Starting OpenVZ
10. Installing OS Template Cache & Template Utilities
11. Alternative Use Precreated Template Cache
12. Create a Container/VPS Machine

We start with Configure YUM to have a OpenVZ repository
Login as root into your server

Download & Install OpenVZ Kernel

You can download other kernel from this URL http://openvz.org/download/kernel/

Note : if your server have memory > 4GB, you need to using PAE kernel

Configure Boot Loader

Configure Sysctl

Disabled SELinux

Configure Conntracks

NOTE : In kernels later than 2.6.8, connection tracking is enabled by default.

Rebooting into your new OpenVZ Kernel
$reboot

Installing OpenVZ Utilities

OpenVZ need 2 utilities below :

vzctl
A utility to control OpenVZ containers (create, destroy, start, stop, set parameters etc.)
vzquota
A utility to manage quotas for containers. Mostly used indirectly (by vzctl).

Using Yum to install vzctl and vzquota
$yum install vzctl vzquota

Starting OpenVZ

Next Step is Installing OS Template cache and Template Utilities

Installing Template Utilites
$yum install vzpkg vzyum vzrpm43-python vzrpm44-python vzctl-lib

Installing OS Template Metadata
$yum search vztmpl

Note : you will see few OS Template Metadata such as vztmpl-Fedora-core6-default, etc.
$yum install vztmpl-fedora-core6-default

Alternative Use Precreated Template Cache

Note : You can download other Precreated Template from this URL http://download.openvz.org/template/precreated/

After we have a precreated Template Cache, Next we can create a container or VPS Machine.

There are several different forms of virtualization that need to be understood as a basis for making the right technology choice.

• Server Hardware Virtualization. Also known as a hypervisor, Server Hardware Virtualization runs a very lightweight core operating system. The hypervisor can host independent virtual machines (VMs). This form of virtualization requires hardware that has embedded virtualization awareness capabilities. Since the hypervisor is very lightweight, there is little overhead in the system, which allows for more scalability in the virtual machines.
• Server Software Virtualization. An operating system, such as Windows Server® 2003 or Windows Server 2008, runs an application that is able to host virtual machines. Each virtual machine runs a completely separate operating system and application set.
• Presentation Virtualization. Centralized systems host multiple user sessions, and all processing is done on those host systems. The user sessions are isolated from each other. Only the presentation information, such as keyboard and mouse inputs, and video updates are sent between the client and the host system. The client can be a full Windows-based workstation or a Windows-based terminal device.
• Application Virtualization. An application is isolated from the underlying operating system by means of wrapper software that encapsulates it. This allows multiple applications that may have conflicting dynamic link libraries (DLLs) or other incompatibilities to run on the same machine without affecting each other.
• Desktop Virtualization. This is similar to Server Software Virtualization, but it runs on client systems such as Windows Vista®. The client operating system runs a virtualization application that hosts virtual machines. This is often used when a specific person needs to run one or a limited number of legacy applications on a legacy operating system.

When creating a new Virtuozzo Container, the following configuration parameters are mandatory and must be selected every time:

• Sample configuration name. Virtuozzo Containers software comes with a set of sample configurations that are installed on the Hardware Node at the time the Virtuozzo Containers software is installed. XML API provides the env_samplem/get_sample_conf call to retrieve the list of the available configurations. In the example provided in this section, the C# equivalent of that call is the env_samplemBinding.get_sample_conf() method.
• Operating System Template. The list of the available templates can be retrieved using the vzapkgm.get_list XML API call. The C# equivalent is vzapkgmBinding.get_list call. For simplicity, we are not including this call in the example because Virtuozzo Containers for Windows currently comes with just one OS template, and Virtuozzo for Linux has one template for each supported Linux distribution. For example, the standard Red Hat Linux OS template name is redhat-as3-minimal.

The rest of the parameters that we use in this example are optional but are typically used when a new Container is created. The following sample shows how to create a Virtuozzo Container.

Sample Function Parameters:

Sample Function:

/// <summary>

/// Sample function CreateCT.

/// Creates a new Virtuozzo Container.

/// </summary>

/// <param name=”name”>Container name.</param>

/// <param name=”os_template”>OS template name.</param>

/// <param name=”platform”>Operating system type: linux or windows.</param>

/// <param name=”architecture”>CPU architecture (x86, ia64)</param>

/// <param name=”hostname”>Container hostname.</param>

/// <param name=”ip”>Container IP address.</param>

/// <param name=”netmask”>Netmask.</param>

/// <param name=”network”>Network interface ID.</param>

/// <param name=”offline_management”>

/// A flag specifyin whether to turn the “offline management”

/// feature on or off.

/// </param>

/// <returns>Server ID of the new Container.</returns>

public string CreateCT(string name, string os_template, string platform, string architecture, string hostname, string ip, string netmask, string network, bool offline_management)

{

try {

// Instantiate the proxy class.

vzaenvmBinding env = (vzaenvmBinding)binder.InitBinding(typeof(vzaenvmBinding));

// The main input object.

create create_input = new create();

// Container configuration information.

venv_configType1 veconfig = new venv_configType1();

/* Retrieve the list of sample configurations.

* Select the first one that is compatible with the

* specified platform (Linux, Windows) and CPU architecture.

*/

env_samplemBinding env_sample = (env_samplemBinding)binder.InitBinding(typeof(env_samplemBinding));

get_sample_conf get_sample = new get_sample_conf();

sample_confType[] samples = env_sample.get_sample_conf(get_sample);

if (samples != null) {

foreach (sample_confType sample in samples) {

if (sample.env_config.os != null) {

if (sample.env_config.os.platform == platform && sample.env_config.architecture == architecture) {

// Set sample configuration ID.

veconfig.base_sample_id = sample.id;

break;

}

}

}

}

// Set OS template.

templateType osTemplate = new templateType();

osTemplate.name = os_template;

veconfig.os_template = osTemplate;

// Set Container name

veconfig.name = name;

// Set Container hostname

veconfig.hostname = hostname;

// Set Container IP address and netmask.

ip_addressType[] ip_address = new ip_addressType[1];

ip_address[0] = new ip_addressType();

ip_address[0].ip = ip;

ip_address[0].netmask = netmask;

// Set network.

net_vethType[] net = new net_vethType[1];

net[0] = new net_vethType();

net[0].host_routed = new object();

net[0].id = network;

net[0].ip_address = ip_address;

veconfig.net_device = net;

// Set the offline management feature.

veconfig.offline_managementSpecified = true;

veconfig.offline_management = offline_management;

// Finalize the new Container configuration.

create_input.config = veconfig;

// Create the Container.

return env.create(create_input).env.eid;

}

catch (Exception e) {

return “Exception: ” + e.Message;

}

}

The function invocation example:

createCT(”sample_ve”, “redhat-as3-minimal”, “linux”,”x86″, “sample_ve_hostname”, “10.16.3.179″, “255.255.255.0″, “venet0″, true );

Burstable RAM can be provided to users of Virtual Private Servers. Each Virtual Private Server has a guaranteed amount of RAM that it’s able to use at all times. At times it is possible that the usage may exceed the allotted amount of guaranteed RAM available, this is when Burstable RAM comes into play. Burstable RAM is provided to the user during times of high usage or traffic. This RAM is not in use by any VPS on a server and can be allocated to any VPS that may need it as long as it is available. So as long as those resources are available, you as a user will be able to go over that limit of guaranteed RAM.

In other words Burstable RAM is the RAM your VPS has the ability to use but it isn’t guaranteed to. Basically it’s for spikes in usage not consistent usage like Guaranteed RAM. For Example your if VPS has 384 MB Guaranteed RAM, and 1024MB Burstable RAM. This means that after you have used up your guaranteed ram, there is still 640MB Burstable RAM available for burst usage. For this reason we always keep some extra memory available on each server at all times as Burstable RAM.

Burstable RAM is never guaranteed to be available and should not be constantly depended upon for Virtual Private Server operation. If your VPS constantly requires greater resources than your package guarantees, we can quickly arrange an upgrade for you to a vps hsoting plan with greater guaranteed resources.

The Hardware Node requirements for the standard 32-bit edition of OpenVZ are :
1) Firstly, the computer should satisfy the Red Hat Enterprise Linux or Fedora Core hardware requirements.
2) IBM PC-A compatible computer is recommended.
3) CPUs: CPU used for VPS would be Intel Celeron, Pentium II, Pentium III, Pentium 4, Xeon, or AMD Athlon CPU. The more Virtual Private Servers you plan to run simultaneously, the more CPUs you need.

4) Memory: Minimum 128 MB of RAM. The more memory, the more Virtual Private Servers you can run. The exact figure depends on the number and nature of applications you are executing in your Virtual Private Servers. However, on the average, at least 1 GB of RAM is always preferable for every 20-30 Virtual Private Servers.

5) Hard Disk Drive: Minimum 4 GB of free disk space is recommended. Each Virtual Private Server occupies 400-600 MB of hard disk space for system files in addition to the user data inside the Virtual Private Server. It should be considered while planning disk division and the number of Virtual Private Servers to run.

6) NIC: Network card will be either Intel EtherExpress100 (i82557-, i82558- or i82559-based) or 3Com(3c905 or 3c905B or 3c595) or RTL8139-based are always preferable.A typical two-way Dell PowerEdge 1650 1u-mountable server with 1 GB of RAM and 36 GB of hard drives is suitable for hosting 30 Virtual Private Servers.

Following are some (possibly overlapping) representative reasons for and benefits of virtualization:

• Virtual machines can be used to consolidate the workloads of several under-utilized servers to fewer machines, perhaps a single machine (server consolidation). Related benefits (perceived or real, but often cited by vendors) are savings on hardware, environmental costs, management, and administration of the server infrastructure.
• The need to run legacy applications is served well by virtual machines. A legacy application might simply not run on newer hardware and/or operating systems. Even if it does, if may under-utilize the server, so as above, it makes sense to consolidate several applications. This may be difficult without virtualization as such applications are usually not written to co-exist within a single execution environment (consider applications with hard-coded System V IPC keys, as a trivial example).
• Virtual machines can be used to provide secure, isolated sandboxes for running untrusted applications. You could even create such an execution environment dynamically - on the fly - as you download something from the Internet and run it. You can think of creative schemes, such as those involving address obfuscation. Virtualization is an important concept in building secure computing platforms.
• Virtual machines can be used to create operating systems, or execution environments with resource limits, and given the right schedulers, resource guarantees. Partitioning usually goes hand-in-hand with quality of service in the creation of QoS-enabled operating systems.
• Virtual machines can provide the illusion of hardware, or hardware configuration that you do not have (such as SCSI devices, multiple processors, …) Virtualization can also be used to simulate networks of independent computers.
• Virtual machines can be used to run multiple operating systems simultaneously: different versions, or even entirely different systems, which can be on hot standby. Some such systems may be hard or impossible to run on newer real hardware.
• Virtual machines allow for powerful debugging and performance monitoring. You can put such tools in the virtual machine monitor, for example. Operating systems can be debugged without losing productivity, or setting up more complicated debugging scenarios.
• Virtual machines can isolate what they run, so they provide fault and error containment. You can inject faults proactively into software to study its subsequent behavior.
• Virtual machines make software easier to migrate, thus aiding application and system mobility.
• You can treat application suites as appliances by “packaging” and running each in a virtual machine.
• Virtual machines are great tools for research and academic experiments. Since they provide isolation, they are safer to work with. They encapsulate the entire state of a running system: you can save the state, examine it, modify it, reload it, and so on. The state also provides an abstraction of the workload being run.
• Virtualization can enable existing operating systems to run on shared memory multiprocessors.
• Virtual machines can be used to create arbitrary test scenarios, and can lead to some very imaginative, effective quality assurance.
• Virtualization can be used to retrofit new features in existing operating systems without “too much” work.
• Virtualization can make tasks such as system migration, backup, and recovery easier and more manageable.
• Virtualization can be an effective means of providing binary compatibility.
• Virtualization on commodity hardware has been popular in co-located hosting. Many of the above benefits make such hosting secure, cost-effective, and appealing in general.
• Virtualization is fun.
• Plenty of other reasons …

A virtual private server (VPS, also referred to as Virtual Dedicated Server or VDS) is a method of partitioning a physical server computer into multiple servers such that each has the appearance and capabilities of running on its own dedicated machine. Each virtual server can run its own full-fledged operating system, and each server can be independently rebooted

The practice of partitioning a single server so that it appears as multiple servers has long been common practice in mainframe computers, but has seen a resurgence lately with the development of virtualization software and technologies for other architectures.

OVERVIEW

The physical server boots normally. It then runs a program that boots each virtual server within a virtualization environment (similar to an emulator). The virtual servers have no direct access to hardware and are usually booted from a disk image.

There are two kinds of virtualizations: software based and hardware based. In a software based virtualization environment, the virtual machines share the same kernel and actually require the main node’s resources. This kind of virtualization normally has many benefits in a web hosting environment because of quota incrementing and decrementing in real time with no need to restart the node. The main examples are Xen,Virtuozzo, HyperVM, Vserver, and OpenVZ which is the core kernel of both Virtuozzo and HyperVM.

In a hardware based virtualization, the virtualization mechanism partitions the real hardware resources. In typical implementations, no burst and/or realtime quota modification is possible; the limits are hard and can only be modified by restarting a virtual machine instance^{[citation needed]}. This kind of environment is potentially more secure in the sense that it is less subject to “Quality of Service crosstalk” between VM instances^{[citation needed]}; on the other hand, its security is typically dependent on the correctness of a larger and more complicated Trusted Computing Base^{[citation needed]}. It is more commonly used in enterprise/commercial deployments^{[citation needed]}. Examples include Microsoft Virtual Server, VMware ESX Server, and Xen.

USES

Virtual private servers bridge the gap between shared web hosting services and dedicated hosting services, giving independence from other customers of the VPS service in software terms but at less cost than a physical dedicated server. As a VPS runs its own copy of its operating system, customers have superuser-level access to that operating system instance, and can install almost any software that runs on the OS. Certain software does not run well in a virtualized environment, including firewalls, anti-virus clients, and indeed virtualizers themselves; some VPS providers place further restrictions, but they are generally lax compared to those in shared hosting environments. Due to the number of virtualization clients typically running on a single machine, a VPS generally has limited processor time, RAM, and disk space.

Due to their isolated nature, VPSes have become common sandboxes for possibly-insecure public services or update testing. For example, a single physical server might have two virtual private servers running: one hosting the production-level (live) website, and a second which houses a copy of it. When updates to crucial parts of software need to be made, they can be tested in the second VPS, allowing for detailed testing to be conducted without requiring several physical servers.

Virtual private servers are also sometimes employed as honeypots, allowing a machine to deliberately run software with known security flaws without endangering the rest of the server. Multiple honeypots can be quickly set up via VPSes in this fashion.

Virtual private server hosting

A growing number of companies offer virtual private server hosting, or virtual dedicated server hosting as an extension for Web hosting services. Some web hosting companies call a Virtual Private Server a Virtual Dedicated Server/Dynamic Dedicated Server or the other way around.

Managed Hosting

Tools are provided to monitor and control the virtual machine.

Unmanaged Hosting

Typically only minimal services are provided, such as ssh console and reboot. Unmanaged VPS hosting is generally less expensive than managed VPS hosting.

Unmetered Hosting

Similar to unmanaged hosting but a fixed bitrate is offered so that it is not possible to exceed a monthly budget.

Virtualization software

For some of the software packages commonly used to provide virtualization, see comparison of virtual machines.

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Above info received from :-http://en.wikipedia.org/