Hypervisors. What is it and how does a virtual server work?
The story of how software being separated from hardware gave us virtualization and a cloud computing environment.
Hypervisor technology is often overlooked, giving preference to the more popular and trendy concept of virtualization. But believe me, you will not be able to get real pleasure from using virtualization until you understand what a hypervisor is and how it works in a computing system.
Many words have already been said about the advantages of virtual server and cloud computing, and a huge number of articles have been written, so many that it seems that this technology is already outdated in the rapidly developing world of IT infrastructure. However, it’s still worth taking such thoughts out of your head, because the hypervisor technology can help to stimulate innovation in the world of cloud computing.
A hypervisor is a process that separates the computer's operating system and applications from the underlying physical hardware. Usually it is a software, although embedded hypervisors are also being created, for example, for mobile devices.
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The hypervisor is the driving force behind the concept of VPS and virtualization, allowing the physical host computer to manage multiple virtual machines as guest OSs, which in turn helps maximize the utilization of computing resources, such as memory, network bandwidth and processor cycles.
In the late 1960s and until the 1970s, most virtualization systems and hypervisors were seen on mainframes developed by IBM. They were used to develop processes for using a computer in time-sharing mode, to test new operating systems and ideas for their improvement or even to study new hardware concepts. Virtualization has allowed programmers to deploy systems and troubleshoot without jeopardizing the stability of the main production system, and besides, it has allowed to avoid the deployment of additional expensive systems.
In the mid-2000s, hypervisors reached a new level when Unix, Linux, and other Unix-like operating systems began using virtualization technologies. What are the reasons for the growing interest in hypervisors and virtualization? Well, first of all, the reason was to improve the hardware and power capabilities that would now allow one machine to perform more synchronized work; secondly, increased cost control, which led to server consolidation; thirdly, security and reliability played a significant role due to the improvement of the hypervisor architecture; and of course the last, but no less important reason is the ability to run OS-dependent applications in various hardware or operating environments. In addition, in 2005, processor developers began to add hardware virtualization to their x86-based products, expanding the availability (and benefits) of virtualization for PCs and server audiences.
Although virtual machines can run on the same physical hardware, they are still logically separate from each other. This means the following: if an error occurred on one virtual machine, a system failure, or a malicious attack, then it does not spread to other virtual machines, regardless of whether they are installed on the same computer or on other physical machines.
Virtual machines are also very mobile — since they are independent of the underlying hardware, they can be moved or moved between local or remote virtual servers. And it is much easier to do this compared to traditional applications tied to physical equipment.
There are two types of hypervisors with very "creative" names "TYPE 1" or "TYPE 2". Type 1 hypervisors, sometimes referred to as “autonomous hypervisors,” run directly on host hardware to control hardware and control guest virtual machines. The first type of modern hypervisors are: Xen, Oracle VM Server for SPARC, Oracle VM Server for x86, Microsoft Hyper-V and VMware ESX / ESXi. By the way, Hyper-V, by the way, runs all VDS Windows servers hosted on VSP.house .
Type 2 hypervisors, sometimes called “host hypervisors,” run on a normal OS, like other applications in the system. In this case, the guest OS runs as a process on the host, and the hypervisors separate the guest OS and the host OS. Examples of the second type of hypervisors: VMware Workstation, VMware Player, VirtualBox, and Parallels Desktop for Mac.
At the moment, there are three main major hypervisor developers: VMware, Microsoft, and Citrix Systems.
In recent years, container technology has become popular as a possible replacement for hypervisors. The reason is that they can host more applications on a single physical server than a virtual machine.
One of the publicists in an article in 2016 for Network World gave an interesting opinion. He said that virtual machines use a lot of system resources, because each virtual machine runs not only a full copy of the operating system, but also a virtual copy of all the hardware on which the operating system should run. Accordingly, the need quickly arises to use a large number of storage devices and machine cycles. And all that is required for a container is an operating system that supports programs and directories, as well as system resources for running a specific program.
However, you should not think that containers will necessarily replace hypervisors and virtual machines, because there are problems of security and practical use of virtual machines. Most likely, companies will use both methods together. And by the way about security, some people think that containers are less secure than hypervisors. The reason is that in containers there is only one OS that applications use, while virtual machines isolate not only applications, but also the OS. If one of the applications is compromised, it can attack the OS in the container, which in turn affects other applications. At the same time, if an application becomes vulnerable in a virtual machine, it can only have a malicious effect on one OS on the server, while other applications or an OS on the virtual machine remain safe.
Although due to many precautions, hypervisors are considered more secure than containers, this does not mean that hypervisors do not have any security problems at all. For example, in theory, hackers can create malware and rootkits that are installed under the OS as a hypervisor. This process, known as “overjacking,” is difficult to detect, since malware can intercept actions of the operating system (for example, entering a password) without the need to protect against malware, since this malware is already running under the OS.
Professionals in the virtualization world can endlessly debate and debate about whether the presence of a rootkit can be detected at the hypervisor base. Several approaches have already been created on this topic, some have introduced the malware concept (SubVirt and Blue Pill), others have demonstrated the Hooksafe anti-rootkit, which effectively protects the OS from root-mode rootkits without noticeable performance losses.
The concept of hypervisors is not limited to server operation. For example, repository hypervisors use the same concept, applying it to a data repository. The storage hypervisor can run on physical hardware, like a virtual machine, inside the hypervisor operating system or on a larger storage network. Storage hypervisors, like normal hypervisors, can work on specific hardware or be hardware independent.
In addition to storage, hypervisors are key to other virtualization processes, including desktop virtualization, OS virtualization, and application virtualization.
Also embedded embedded hypervisors. What is it? Embedded hypervisors support embedded system requirements. They are slightly different from server-based and desktop-based hypervisors. The embedded hypervisor is embedded into the embedded device from the very beginning, rather than being loaded upon subsequent deployment of the device. In an embedded system, the various components typically function together to ensure the functionality of the device.
Hypervisor technology is often overlooked, giving preference to the more popular and trendy concept of virtualization. But believe me, you will not be able to get real pleasure from using virtualization until you understand what a hypervisor is and how it works in a computing system.
Many words have already been said about the advantages of virtual server and cloud computing, and a huge number of articles have been written, so many that it seems that this technology is already outdated in the rapidly developing world of IT infrastructure. However, it’s still worth taking such thoughts out of your head, because the hypervisor technology can help to stimulate innovation in the world of cloud computing.
What is a hypervisor?
A hypervisor is a process that separates the computer's operating system and applications from the underlying physical hardware. Usually it is a software, although embedded hypervisors are also being created, for example, for mobile devices.
')
The hypervisor is the driving force behind the concept of VPS and virtualization, allowing the physical host computer to manage multiple virtual machines as guest OSs, which in turn helps maximize the utilization of computing resources, such as memory, network bandwidth and processor cycles.
Hypervisor history
In the late 1960s and until the 1970s, most virtualization systems and hypervisors were seen on mainframes developed by IBM. They were used to develop processes for using a computer in time-sharing mode, to test new operating systems and ideas for their improvement or even to study new hardware concepts. Virtualization has allowed programmers to deploy systems and troubleshoot without jeopardizing the stability of the main production system, and besides, it has allowed to avoid the deployment of additional expensive systems.
In the mid-2000s, hypervisors reached a new level when Unix, Linux, and other Unix-like operating systems began using virtualization technologies. What are the reasons for the growing interest in hypervisors and virtualization? Well, first of all, the reason was to improve the hardware and power capabilities that would now allow one machine to perform more synchronized work; secondly, increased cost control, which led to server consolidation; thirdly, security and reliability played a significant role due to the improvement of the hypervisor architecture; and of course the last, but no less important reason is the ability to run OS-dependent applications in various hardware or operating environments. In addition, in 2005, processor developers began to add hardware virtualization to their x86-based products, expanding the availability (and benefits) of virtualization for PCs and server audiences.
Advantages of hypervisors
Although virtual machines can run on the same physical hardware, they are still logically separate from each other. This means the following: if an error occurred on one virtual machine, a system failure, or a malicious attack, then it does not spread to other virtual machines, regardless of whether they are installed on the same computer or on other physical machines.
Virtual machines are also very mobile — since they are independent of the underlying hardware, they can be moved or moved between local or remote virtual servers. And it is much easier to do this compared to traditional applications tied to physical equipment.
There are two types of hypervisors with very "creative" names "TYPE 1" or "TYPE 2". Type 1 hypervisors, sometimes referred to as “autonomous hypervisors,” run directly on host hardware to control hardware and control guest virtual machines. The first type of modern hypervisors are: Xen, Oracle VM Server for SPARC, Oracle VM Server for x86, Microsoft Hyper-V and VMware ESX / ESXi. By the way, Hyper-V, by the way, runs all VDS Windows servers hosted on VSP.house .
Type 2 hypervisors, sometimes called “host hypervisors,” run on a normal OS, like other applications in the system. In this case, the guest OS runs as a process on the host, and the hypervisors separate the guest OS and the host OS. Examples of the second type of hypervisors: VMware Workstation, VMware Player, VirtualBox, and Parallels Desktop for Mac.
At the moment, there are three main major hypervisor developers: VMware, Microsoft, and Citrix Systems.
Containers versus hypervisors
In recent years, container technology has become popular as a possible replacement for hypervisors. The reason is that they can host more applications on a single physical server than a virtual machine.
One of the publicists in an article in 2016 for Network World gave an interesting opinion. He said that virtual machines use a lot of system resources, because each virtual machine runs not only a full copy of the operating system, but also a virtual copy of all the hardware on which the operating system should run. Accordingly, the need quickly arises to use a large number of storage devices and machine cycles. And all that is required for a container is an operating system that supports programs and directories, as well as system resources for running a specific program.
However, you should not think that containers will necessarily replace hypervisors and virtual machines, because there are problems of security and practical use of virtual machines. Most likely, companies will use both methods together. And by the way about security, some people think that containers are less secure than hypervisors. The reason is that in containers there is only one OS that applications use, while virtual machines isolate not only applications, but also the OS. If one of the applications is compromised, it can attack the OS in the container, which in turn affects other applications. At the same time, if an application becomes vulnerable in a virtual machine, it can only have a malicious effect on one OS on the server, while other applications or an OS on the virtual machine remain safe.
Hypervisor Security Issues
Although due to many precautions, hypervisors are considered more secure than containers, this does not mean that hypervisors do not have any security problems at all. For example, in theory, hackers can create malware and rootkits that are installed under the OS as a hypervisor. This process, known as “overjacking,” is difficult to detect, since malware can intercept actions of the operating system (for example, entering a password) without the need to protect against malware, since this malware is already running under the OS.
Professionals in the virtualization world can endlessly debate and debate about whether the presence of a rootkit can be detected at the hypervisor base. Several approaches have already been created on this topic, some have introduced the malware concept (SubVirt and Blue Pill), others have demonstrated the Hooksafe anti-rootkit, which effectively protects the OS from root-mode rootkits without noticeable performance losses.
Empowering the hypervisor
The concept of hypervisors is not limited to server operation. For example, repository hypervisors use the same concept, applying it to a data repository. The storage hypervisor can run on physical hardware, like a virtual machine, inside the hypervisor operating system or on a larger storage network. Storage hypervisors, like normal hypervisors, can work on specific hardware or be hardware independent.
In addition to storage, hypervisors are key to other virtualization processes, including desktop virtualization, OS virtualization, and application virtualization.
Also embedded embedded hypervisors. What is it? Embedded hypervisors support embedded system requirements. They are slightly different from server-based and desktop-based hypervisors. The embedded hypervisor is embedded into the embedded device from the very beginning, rather than being loaded upon subsequent deployment of the device. In an embedded system, the various components typically function together to ensure the functionality of the device.
Source: https://habr.com/ru/post/349788/
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