What is the process of dividing a physical server into several virtual servers called virtual private servers?

In computing, a single, physical server can be segmented into multiple isolated and individual virtual servers through some form of software. Each of these virtual servers is fully capable of independently running its own operating system (OS).

Among other reasons, this is done primarily for tighter controls over all server users. Server virtualization means that users can only access resources assigned to their unique instance.

For example, users on a virtualized server can’t identify the total number of operating systems, processors, or other virtualized servers on the physical server.

Additionally, they can only use the maximum memory or CPU cycles associated with their instance, preventing them from affecting other users on the server.

Servers are computers that process requests from other computers within a network. Classically, one server is dedicated to one task or application. Considering just how many tasks and applications there are, this can add up to an unmanageable number of servers within one network.

Servers take up space and power to run. What’s more, some modern servers have more resources (memory and storage) than they need to handle the dedicated tasks or applications required. This underutilization of computing power across many servers can end up using far more energy than is necessary. Essentially, servers need to be managed in a way that allows for efficient energy consumption without sacrificing computing capabilities.

VPS Server Hosting is one example of server virtualization.

Server virtualization mitigates server inefficiencies by using software to divide a single physical server into multiple fully isolated virtual servers. Each of those virtual servers is capable of running independent operating systems and completing tasks by dividing up the resources across the parent server.

Virtualization can greatly benefit an organization. In addition to streamlining network needs, server virtualization benefits include:

Not everything is perfect with server virtualization. Some drawbacks to virtualization include:

Server virtualization is widespread as a solution across organizations and industries. This is because it solves some big problems like managing server resources, saving on infrastructure costs, and alleviating demand on IT. There are several types of server virtualization that network administrators rely on. Types of server virtualization examples include:

With full virtualization, a type of software called a hypervisor splits up the server’s resources between completely independent virtual servers that are isolated from each other. The hypervisor handles how resources are allocated between each virtual server. Since the virtual machines are separate, they all run on their own operating systems and can be configured as needed.

Learn more about virtualization for CentOS and Ubuntu, which are both Linux-based OS.

Para-virtualization is somewhat related to full virtualization in that a hypervisor can access virtual machines through interfaces that are highly similar to the underlying hardware. Prior to installation inside a virtual machine, para-virtualization involves modifying a guest operating system to allow all other guest OS on the server to share resources and communicate with one another. Because all the VMs are working together, there are fewer demands on the hypervisor, meaning more of the virtualization server’s resources are dedicated to the virtual servers.

With hardware-assisted virtualization, the division of resources needed to support multiple VMs is already built into the CPU of the host server. This allows virtual machines to communicate directly to the main server rather than entirely through the hypervisor. It’s a way to partially cut out the middleman, though a hypervisor is still needed. Since the path between the virtual machines and the physical server is more direct, the hypervisor uses a very significant amount of the server’s resources. This makes it seem like the virtual machines are running directly on the server.

With full virtualization, para-virtualization, and hardware-assisted virtualization, a hypervisor is needed to provide a platform on which virtual servers’ operating systems can run. With OS-level virtualization, however, the host server’s operating system is set up to allow for multiple instances of virtual machines called containers. The VMs operate in much the same way in OS-level virtualization as in hypervisor virtualization, but the computing overhead of the host operating system is a much higher percentage of the physical server’s resources than in a hypervisor-based system. However, OS-level virtualization can be simpler and less costly for a new user to implement.

With hypervisor-based virtualization, software (the hypervisor) virtually emulates the hardware of the main server, basically acting like the physical machine on which operating systems can run. The hypervisor allocates resources of the physical server across the various guest virtual machines.

Full virtualization and para-virtualization are types of hypervisor-based virtualization. Hardware-assisted virtualization is a type of hybrid virtualization that is hypervisor-based as well as hardware-based.

Virtualized servers can help improve an organization’s computing systems in multiple ways. They allow IT to concentrate less time on the internal network, save space in the data center, maximize server resources, and cut costs associated with hardware and energy. On top of all that, setting up a virtual machine is much simpler than setting up a new physical server.

However, server virtualization is often associated with shared server resources or multi-tenant solutions. While multi-tenant servers are more cost effective and can be very powerful, they are often associated with possible challenges like noisy neighbors and additional security or stability issues.

One way to mitigate these risks is to choose a bare-metal virtualization approach. With bare metal virtualization, you are the single tenant using the server’s resources, even though there is still a hypervisor managing the virtual servers. Bare metal virtualization can give you all the benefits of cloud computing while minimizing the risks associated with shared server configurations.

While it’s possible to set up your own hypervisor or OS-level virtualization in your local server room, you don’t have to run your virtual machines on your own private on-premises physical servers. Liquid Web offers a variety of hosting options to fit your needs.

At the entry level, you could select a traditional bare metal server and install your own virtualization software. If you need a simple path to taking advantage of bare metal virtualization, our bare metal cloud servers offer single-tenant virtualized servers, giving you the power and performance you need in one package.

If you need the ultimate solution for performance and flexibility, Liquid Web’s VMware Private Cloud will provide you with everything you need. From load balancing to DDOS protection and High Availability Databases, you will have an industry-leading, enterprise solution at your fingertips.

Reach out to one of our Solutions Experts today to start taking advantage of the power of virtualization for all your server hosting needs.

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Server Virtualization is the partitioning of a physical server into a number of small virtual servers, each running its own operating system. These operating systems are known as guest operating systems. These are running on another operating system known as the host operating system. Each guest running in this manner is unaware of any other guests running on the same host. Different virtualization techniques are employed to achieve this transparency.

Types of Server virtualization :

1. Hypervisor –

A Hypervisor or VMM(virtual machine monitor) is a layer that exists between the operating system and hardware. It provides the necessary services and features for the smooth running of multiple operating systems.

It identifies traps, responds to privileged CPU instructions, and handles queuing, dispatching, and returning the hardware requests. A host operating system also runs on top of the hypervisor to administer and manage the virtual machines.

2. Para Virtualization –

It is based on Hypervisor. Much of the emulation and trapping overhead in software implemented virtualization is handled in this model. The guest operating system is modified and recompiled before installation into the virtual machine.
Due to the modification in the Guest operating system, performance is enhanced as the modified guest operating system communicates directly with the hypervisor and emulation overhead is removed.

Example: Xen primarily uses Paravirtualization, where a customized Linux environment is used to support the administrative environment known as domain 0.

Advantages:

Easier
Enhanced Performance
No emulation overhead

Limitations:

Requires modification to a guest operating system

3. Full Virtualization –

It is very much similar to Paravirtualization. It can emulate the underlying hardware when necessary. The hypervisor traps the machine operations used by the operating system to perform I/O or modify the system status. After trapping, these operations are emulated in software and the status codes are returned very much consistent with what the real hardware would deliver. This is why an unmodified operating system is able to run on top of the hypervisor.

Example: VMWare ESX server uses this method. A customized Linux version known as Service Console is used as the administrative operating system. It is not as fast as Paravirtualization.

Advantages:

No modification to the Guest operating system is required.

Limitations:

Complex
Slower due to emulation
Installation of the new device driver is difficult.

4. Hardware-Assisted Virtualization –

It is similar to Full Virtualization and Paravirtualization in terms of operation except that it requires hardware support. Much of the hypervisor overhead due to trapping and emulating I/O operations and status instructions executed within a guest OS is dealt with by relying on the hardware extensions of the x86 architecture.

Unmodified OS can be run as the hardware support for virtualization would be used to handle hardware access requests, privileged and protected operations, and to communicate with the virtual machine.

Examples: AMD – V Pacifica and Intel VT Vanderpool provide hardware support for virtualization.

Advantages:

No modification to a guest operating system is required.
Very less hypervisor overhead

Limitations:

Hardware support Required

5. Kernel level Virtualization –

Instead of using a hypervisor, it runs a separate version of the Linux kernel and sees the associated virtual machine as a user-space process on the physical host. This makes it easy to run multiple virtual machines on a single host. A device driver is used for communication between the main Linux kernel and the virtual machine.
Processor support is required for virtualization ( Intel VT or AMD – v). A slightly modified QEMU process is used as the display and execution containers for the virtual machines. In many ways, kernel-level virtualization is a specialized form of server virtualization.

Examples: User – Mode Linux( UML ) and Kernel Virtual Machine( KVM )

Advantages:

No special administrative software is required.
Very less overhead

Limitations:

Hardware Support Required

6. System Level or OS Virtualization –

Runs multiple but logically distinct environments on a single instance of the operating system kernel. Also called shared kernel approach as all virtual machines share a common kernel of host operating system. Based on the change root concept “chroot”. chroot starts during bootup. The kernel uses root filesystems to load drivers and perform other early-stage system initialization tasks. It then switches to another root filesystem using chroot command to mount an on-disk file system as its final root filesystem and continue system initialization and configuration within that file system. The chroot mechanism of system-level virtualization is an extension of this concept. It enables the system to start virtual servers with their own set of processes that execute relative to their own filesystem root directories.

The main difference between system-level and server virtualization is whether different operating systems can be run on different virtual systems. If all virtual servers must share the same copy of the operating system it is system-level virtualization and if different servers can have different operating systems ( including different versions of a single operating system) it is server virtualization.

Examples: FreeVPS, Linux Vserver, and OpenVZ are some examples.

Advantages:

Significantly lightweight than complete machines(including a kernel)
Can host many more virtual servers
Enhanced Security and isolation
Virtualizing an operating system usually has little to no overhead.
Live migration is possible with OS Virtualization.
It can also leverage dynamic container load balancing between nodes and clusters.
On OS virtualization, the file-level copy-on-write (CoW) method is possible, making it easier to back up data, more space-efficient, and easier to cache than block-level copy-on-write schemes.

Limitations: