Many people forget the importance of hypervisor technology. You can't fully experience the benefits of virtualization without understanding the nature of a server hypervisor and its role in a computer system.
What is a hypervisor in simple words
A hypervisor is an important piece of software that provides a reliable separation of the computer operating system and applications from the physical hardware. It is a crucial link in the architecture of a computer system, acting as an intermediary between hardware and software. The main purpose of server hypervisor is to ensure efficient resource utilization and provide an isolated environment for operating systems and applications.
What hypervisors are for
The hypervisor allows the physical host computer to manage multiple VPS virtual machines as guest OSes, which in turn allows for efficient utilization of computing resources.
Advantages of a hypervisor
A hypervisor abstracts a host's operating software environment from its hardware component. IT can freely configure, install, and manage software applications without being limited by the hardware configuration.
Efficiency. Instead of a time-consuming and labor-intensive manual installation process, the hypervisor can be quickly configured to instantly create a virtualized environment.
Security. Powerful mechanisms to isolate virtual machines and keep them secure. Each virtual environment runs in its own container. This ensures that problems like a failure or attack on a virtual machine won't affect others.
Scalability. The need for additional resources can be met by simply configuring multiple virtual machines, without the need to purchase and configure new hardware. When an application requires additional processing power, the hypervisor provides seamless access to free physical resources.
What the hypervisor does
The software is installed on physical servers. The terminology that is used to describe the process includes the terms host, which is a physical machine, and guests, which are virtual operating systems.
The main task of a hypervisor is to create multiple virtual copies of a physical computer. Each of them has its own hardware resources and is perceived by the user as a separate device. The hypervisor allows you to install an isolated guest operating system on each virtual machine, independent of the host machine's hardware.
Types of hypervisors
Hypervisors of the first type are standalone programs that are installed directly on the server hardware. They have direct access to hardware resources and do not need a host operating system. Work directly with physical hardware and can manage computing resources for multiple virtual machines. Provide high performance and security because the absence of a host operating system reduces the risk of failures or vulnerabilities. Examples include Hyper-V, KVM, and ESXi.
Type 2 hypervisors are installed on top of an existing operating system on the host machine. Examples - Oracle Virtual Box, VMware Workstation, OpenVZ. They provide and manage virtual resources for guest operating systems. They are more flexible and easier to install, but due to the need to access the host operating system, they have lower performance. Hybrid hypervisors are also available.
Can we do without a hypervisor
You can create virtual containers using containerization. The main difference is that each virtual machine requires its own operating system, while containers directly use a single OS kernel. Less system resources are required compared to virtual machines. They start up faster, move easily between different environments, and take up less space. But containerization has a big disadvantage - the inability to properly allocate resources between containers, i.e. the load created within one container always affects the others.
Which hypervisor to choose for the server
VMware vSphere
The program supports various operating systems, including Linux, macOS, Windows and FreeBSD. To install on the server, you need to download the distribution from a flash card or disk. You can use the program for free for 60 days, after which you need to purchase a licensed version or stay on the demo version with limited features. While the free version has no physical hardware limitations in terms of memory and processors, there are other issues. For example, you can't use the program together with Veeam to create backups or limit the number of cores on a virtual appliance to 8. Also, you can't connect to a vCenter server and a read-only mode is available via API. Tools are available to automate boot processes, network configuration and server connectivity.
An important advantage of the program is the built-in integration with Microsoft Active Directory, which allows you to recognize clients in the private and hybrid cloud. Thanks to the even distribution of resources, you can change the size of the hard disk without rebooting the computer.
One of the features of the hypervisor is its demanding hardware.
Hyper-V
Developed in 2008, it is an efficient solution for creating and augmenting cloud storage.
- Supports working with persistent memory to achieve consistent performance of virtual machines.
- Easy to configure and manage.
- Provides the ability to utilize hidden subnets, allowing secure communication between virtual machines.
Xen
Developed in 2003 in Cambridge represents a serious innovation in virtualization. A Citrix version was released in 2007, extending the capabilities of the platform.
One of the key advantages of Xen is its ability to support hardware virtualization and para-virtualization, which allows you to use system resources more efficiently and create isolated virtual environments for different tasks.
Another major advantage of Xen is its compactness. Most of the code resides outside of the hypervisor, which greatly reduces the size of the hypervisor.
Xen is also an open source program. This allows for continuous improvement and support of the platform, making it flexible and adaptive.
KVM
A powerful and versatile virtualization software tool based on the Linux kernel. You need to download the software and install the Libvirt virtualization library. Then perform a detailed configuration depending on the operating system installed on the physical hardware. The undeniable advantage of the hypervisor is that it works on any server and is not picky about resources.
- It has built-in disaster recovery mechanisms.
- Supports the use of containers, which provides isolation and security for virtualized environments.
- It is the foundation for the Proxmox virtualization system.
- KVM is inexpensive to use, making it accessible to a wide audience.
KVM administration requires some skill and can be complex. There are no graphical tools for managing virtual hardware in the program. However, there is a Virt-Manager package that can be installed for more convenient management.
It is also worth considering that KVM does not have built-in tools similar to Fault Tolerate in VMware. But you can create a high availability cluster using DRBD network replication and secure it with a VPN connection.
Attention! The program has no support service.
VMware
Belongs to the first type, so using the software requires careful selection of the appropriate equipment. The official program manual contains a detailed list of hardware with which compatibility is guaranteed.
Failure to comply with the required parameters in combination with unsuitable hardware may result in unpredictable system behavior, performance degradation and errors.
Recommendations for selecting a hypervisor
Choosing a hypervisor is an important step and following the correct guidelines will help you make an informed choice. You need to consider the physical capabilities of the server, availability of the required licensed version of the software, technical support and other factors.
- Carefully study the available information on the official portal of the software vendor.
- Make sure that the characteristics of your physical machine meet the minimum requirements of the hypervisor.
- Investigate other features of the selected software to make sure it fully meets your needs.
Summary
There is no one-size-fits-all answer to the question of whether a particular hypervisor is preferable, as the choice depends on many factors. If your plans include the use of Linux virtual machines, we recommend XenServer or KVM. These hypervisors provide extensive support for the Linux environment and allow for efficient management of virtual machines.
