In the world of virtualization, hypervisors play a key part, making the basis for creating virtual environments. To efficiently use and manage IT resources, one should fully understand their essence, types, and possibilities. Let’s figure it out.
What is a hypervisor?
Hypervisor is a software for creating virtual machines (VMs), which makes it possible to run several operating systems (OS) on one physical server. It helps in optimizing resources, data safety, seamless work of IT infrastructure and its scalability.
Before hypervisors were on the scene, most computers could simultaneously work with just a single OS. As the computing equipment was meant to process requests only from it, it added to stability. But this approach had its drawbacks, with irrational use of resources due to the operating system not always engaging the whole PC capacity to work.
A hypervisor allows multiple instances of operating systems to run alongside each other, using the same computational resources. This process is called virtualization, and the operating system instances are known as virtual machines (VMs). The hypervisor logically separates the VMs from one another, assigning each its own portion of the core computing power, memory, and storage. This prevents VMs from interfering among themselves. For example, if one VM crashes or experiences a security breach, the others continue to operate unaffected.
Depending on the type, hypervisors run directly on physical hardware or as a software-level application.
History of hypervisors
IBM was the first to use virtualization systems and hypervisors on its mainframes. It happened in the late 1960s. They were used for time-sharing, testing and improving new operating systems, as well as exploring new hardware concepts.
Virtualization enabled the deployment of systems and troubleshooting without threatening the stability of the primary system, avoiding the need to deploy 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.
There were several reasons for the growing interest in hypervisors and virtualization. First, there was an improvement in hardware capabilities that allowed a single machine to perform more synchronized tasks. Second, there was a focus on cost control, leading to server consolidation. Third, security and reliability improved due to enhanced hypervisor architectures. Lastly, hypervisors enabled applications dependent on specific OS environments to run on different hardware or operating systems.
In 2005, processor developers began adding hardware virtualization to their x86-based products, expanding virtualization availability for PCs and servers.
Types of hypervisors
The modern hypervisors are present in two types:
Type 1
It works directly on the physical computer, cooperating with its processors, memory and storage, and is often also dubbed ‘bare’ hypervisor. It substitutes the host’s operating system and is highly efficient due to the direct access to the physical equipment. Likewise, it also enhances the IT infrastructure safety, as there is nothing between it and the central processor that could be corrupted. However, a hypervisor requires a separate machine for administering various virtual machines and managing host equipment.
Popular examples are Microsoft Hyper-V, VMware vSphere, KVM.
Type 2
It runs on top of an operating system. Since it doesn’t directly allocate virtual machine resources based on the core hardware, the process is slower and less efficient.
Resource optimization and management are also less flexible compared to Type 1 hypervisors. For instance, they can’t dynamically allocate computing resources. Let’s say, you assign 8 GB of RAM to a virtual machine, it will always consume exactly that amount.
Despite these downsides, type 2 hypervisors are easier to set up and manage. You can install virtualization technology as an application on a personal system, just like any other computer program.
This type of hypervisor is ideal for running virtual machines with different operating systems for testing or development purposes. Popular examples include Oracle VirtualBox, VMware Fusion, and Windows Virtual PC.
Hypervisor Capabilities
Creating virtual machines. Hypervisors allow users to create multiple isolated virtual instances on a single physical machine. In addition to optimizing costs, server virtualization improves workload distribution.
Resource allocation. Users can use hypervisors to dynamically distribute server resources among virtual instances. This allows other environments to utilize excess computing power for more stable operation.
Snapshot creation. A hypervisor can capture the state of the system and the configuration of a virtual machine at a given point in time. This restore point allows users to easily recover their data after crashes or when cloning server instances.
Real-time migration. Users can move a virtual instance to another physical host without interrupting current processes or causing downtime. Besides simplifying data migration, this feature acts as a failover system, switching a failed system to another server.
Monitoring and managing resources. System administrators can allocate and reallocate hardware resource pools among different instances. Additionally, using hypervisor software, they can easily monitor resource consumption by multiple instances in one place.
Reasons to use hypervisors
Virtualization software that works on the basis of hypervisors has several use cases.
Organizing virtual desktop infrastructure (VDI)
A hypervisor allows users to run various guest operating systems on a server for creating a virtual desktop infrastructure. It provides users with a remote desktop environment, to which they can gain access through a private protocol.
Optimizing resource use
The companies use hypervisors to unite many computers performing different tasks into one server. For example, if sales, marketing, and technical support teams do their workloads on separate physical servers, it can lead to the resources’ idle time. With the help of a hypervisor, virtual machines for relevant departments could be placed on a single server, even if they require different operating systems or software components.
Development and testing environments
The isolation of a hypervisor allows developers to easily create separate environments for development and testing. They can do this by setting up a virtual machine on the same server or their local systems. This enables developers to test new changes in services or applications without affecting the production system. Additionally, they can determine the optimal resource allocation for applications before deploying them on a real server.
Disaster recovery
System administrators commonly use hypervisors for disaster recovery and data protection. Hypervisors offer replication capabilities, allowing them to create mirror copies of existing virtual machines on backup servers. Some of them also replicate data in real-time to minimize its loss. This enables quick migration of virtual machines between hosts if the current system fails, maintaining continuous operation. If a working machine crashes, the hypervisor initiates automatic failover, making the secondary system the new primary host.
