hypervisors - TarisMajor/5143-OpSystems GitHub Wiki
Hypervisor (Operating System)
A hypervisor, also known as a virtual machine monitor (VMM), is a key component in modern computing systems that enables the virtualization of hardware resources. It allows multiple virtual machines (VMs) to run concurrently on a single physical machine, each with its own isolated operating system. Hypervisors abstract the underlying hardware and create a virtualized environment that acts like multiple independent systems.
Hypervisors are widely used in data centers, cloud computing, and various types of virtualized environments to increase resource utilization, improve efficiency, and simplify management.
Types of Hypervisors
Hypervisors can be broadly classified into two categories based on their relationship with the host system:
- Type 1 Hypervisor (Bare-metal Hypervisor) A Type 1 hypervisor operates directly on the physical hardware of the host machine, without needing a host operating system. It is installed on the machine’s hardware, and it is responsible for directly managing hardware resources and allocating them to the virtual machines. This type of hypervisor provides better performance and security because it does not rely on a host operating system.
Examples:
VMware ESXi Microsoft Hyper-V Xen KVM (Kernel-based Virtual Machine), when running as part of Linux. Advantages:
Better performance due to direct access to hardware. Increased security, as there is no host OS to be exploited. Use Cases:
Enterprise environments and data centers.
Cloud computing platforms, like private clouds and large-scale virtualized environments. 2. Type 2 Hypervisor (Hosted Hypervisor) A Type 2 hypervisor runs as a software layer on top of a host operating system, rather than directly on the hardware. This means that the host operating system manages the hardware and allocates resources to the hypervisor, which in turn assigns resources to virtual machines. While Type 2 hypervisors are often easier to set up and use, they typically have lower performance compared to Type 1 because of the additional layer of the host operating system.
Examples: VMware Workstation Oracle VirtualBox Parallels Desktop Advantages: Easier to set up and manage since they leverage existing operating systems. Suitable for personal use and development environments. Use Cases: Development and testing environments. Home labs and non-enterprise applications. Key Functions of Hypervisors Hypervisors provide several important features that are essential for virtualization:
Resource Allocation:
Hypervisors allocate physical resources (such as CPU, memory, and storage) to virtual machines. The management of these resources ensures that each VM has the necessary capabilities to run applications effectively, while preventing conflicts between VMs. Isolation:
Each virtual machine operates in its own isolated environment, meaning the applications and processes inside a VM are isolated from those in other VMs. This prevents VMs from interfering with each other and enhances security, as a failure or attack in one VM does not affect others. Virtual Device Management:
Hypervisors provide virtual devices such as virtual network interfaces, hard disks, and display adapters to the virtual machines. These virtual devices mimic real hardware, enabling VMs to interact with the virtualized environment as if they were running on a physical machine. VM Migration:
Hypervisors support live migration, which allows running VMs to be moved from one physical machine to another without shutting them down. This is especially useful in load balancing, fault tolerance, and maintenance in cloud and data center environments. Snapshot and Cloning:
Hypervisors allow for the creation of snapshots of virtual machines, which capture the state of a VM at a specific point in time. These snapshots can be used for backup or to roll back to a previous state. Additionally, VMs can be cloned, allowing for easy replication and scaling of virtualized environments. Benefits of Using Hypervisors Improved Resource Utilization:
Hypervisors enable multiple virtual machines to share the same physical hardware, leading to better resource utilization. For example, a physical server that would otherwise be underutilized can run multiple VMs, each handling different tasks or services. Cost Savings:
Virtualization allows organizations to reduce the number of physical servers required, which can result in significant cost savings in terms of hardware, energy consumption, and data center space. Flexibility and Scalability:
Virtual machines are easy to create, modify, and migrate. This flexibility is ideal for testing, development, and scaling applications in cloud environments. Hypervisors also make it easier to quickly deploy or scale new virtual machines as needed. Isolation and Security:
Hypervisors provide a high degree of isolation between virtual machines, which enhances security. If one VM is compromised, the attacker cannot easily affect other VMs, which is crucial for multi-tenant environments such as public clouds. Disaster Recovery and High Availability:
Hypervisors enable features like snapshots, cloning, and live migration, essential for disaster recovery, fault tolerance, and high availability in virtualized environments. Virtual machines can be quickly recovered from backups or migrated to another host in case of failure. Hypervisor Use in Cloud Computing Hypervisors play a central role in cloud computing environments. In public and private clouds, they are used to manage the allocation of resources to various tenants, ensuring that virtualized workloads are distributed efficiently and securely across the cloud infrastructure. Cloud providers such as Amazon Web Services (AWS), Microsoft Azure, and Google Cloud rely on hypervisor technologies to offer Infrastructure as a Service (IaaS) to their customers.
Conclusion A hypervisor is a fundamental technology that enables virtualization, allowing multiple virtual machines to run on a single physical system. There are two primary types of hypervisors: Type 1 (bare-metal) and Type 2 (hosted). Hypervisors provide key benefits, such as improved resource utilization, flexibility, scalability, security, and cost savings. They are essential components in modern IT infrastructures, particularly in cloud computing, data centers, and virtualized environments.
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