Hello, HackerNoon! Today, I’d like to address the topic of virtualization. When discussing virtual environments and their deployment, it's crucial first to understand how they work, the needs they address, and the different types that exist. Today, we will talk about hypervisors.
A hypervisor (or Virtual Machine Monitor, VMM) is software, firmware, or hardware that creates and manages virtual machines (VMs). Each virtual machine installed on a host can run its own operating system; they can also function independently of each other and the host.
There are two different subtypes of virtualization: paravirtualization and full virtualization. How do they differ from each other? Let's start with a brief comparison.
1. Full Virtualization
- Isolation: The guest operating system is completely separated from the virtualization layer and hardware by the virtual machine.
- Operation Methods: Binary translation and direct execution are used.
- Characteristics: Considered less secure and slower, but it provides greater portability and compatibility compared to paravirtualization.
2. Paravirtualization
- Isolation: The guest operating system is partially separated from the virtualization layer and hardware by the virtual machine.
- Operation Methods: Hypercalls are used – calls from the operating system or processes to the hypervisor to perform specific tasks.
- Characteristics: Considered more secure and faster, but less portable and compatible compared to full virtualization.
The process of virtualization is highly valued by many IT organizations because it reduces costs and increases efficiency and productivity. Additionally, virtualization provides improved scalability, enhances reliability, and simplifies IT infrastructure management. It also enables faster application and service deployment, simplifies data backup and recovery, and improves security and access control.
Key Functions of Hypervisors Include:
- Resource Management: Efficient allocation and management of host resources among VMs. Essentially, we separate the capabilities and space of a physical device and allocate them to VMs.
- VM Migration: The ability to move VMs between different hosts without stopping their operation (in the case of Type 1 hypervisors).
- Isolation: A virtual machine can be isolated from other virtual machines on the same physical machine to prevent any security issues and ensure high resource utilization.
- Security: Essentially, virtual machines and their states are files stored on the host. Thus, they can be easily moved/copied (also to another host machine) and checked by antivirus programs.
Native Type
This type of virtualization, also known as a Type 1 (bare-metal) hypervisor, means that the hypervisor is located directly above the hardware, acting as both a hardware and software implementation. In this case, operating systems run on the hypervisor, which manages their access to hardware resources. This type of virtualization is especially typical for server computers as it provides high performance, efficiency, and security.
Examples: VMware ESXi, Citrix XenServer.
Hosted Type
This type of virtualization, also known as a Type 2 (hosted) hypervisor, runs on top of the host operating system. Here, the hypervisor is an application that manages virtual machines, each with its own operating system. This type of virtualization is often used on personal computers and laptops for development, testing, and other purposes requiring multiple operating systems on a single physical device.
Examples: VMware Workstation, Oracle VirtualBox.
Hybrid Type
This type represents an intermediate option between native (bare-metal) and hosted hypervisors. A hybrid hypervisor includes two main components: a thin hypervisor that manages the processor and memory, and a specialized service operating system running on top of it. This architecture allows the combining of the advantages of both approaches, providing high performance and flexibility in managing virtual machines.
Examples: Microsoft Virtual Server, Sun Logical Domains, Microsoft Hyper-V, VMware Workstation.
A Little Bit About Containers
This type, which is not an example of hypervisor virtualization, is implemented in tools like Docker and Kubernetes. In short, containers operate at the operating system level, sharing one kernel of the host OS among all containers. This allows containers to be lightweight and quick to start as they do not include a full-fledged operating system. While containers themselves do not require a hypervisor, they can run inside a virtual machine managed by a hypervisor. This adds an additional level of isolation and security.
Now, let's talk about the usage in the context of different tasks for various engineering specialties:
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Developers: Virtualization allows the creation of isolated environments for development, testing new software versions without risking the main system, and ensuring code compatibility across different OSes and versions. Virtual machines and containers can be quickly deployed with the necessary tools and libraries, speeding up the development process.
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Testers: Virtualization enables running tests in isolated environments, preventing tests from affecting each other, and simplifies test automation and test environment management. Testing software on different operating systems and configurations helps identify more bugs and improve product quality.
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DevOps Engineers: Virtualization simplifies scaling infrastructure, adding and removing resources as needed. Virtualization and containerization facilitate infrastructure as code (IaC) management and deployment, ensuring repeatability and reliability. Containers allow easy movement of applications between different environments (development, testing, production), enhancing flexibility and speeding up the release of new software versions.
In conclusion, virtualization is a versatile and sought-after skill for an engineer, allowing flexible work without being tied to a specific OS in the case of hypervisor variants. If you want to start with something but don't know where, a VM with a VirtualBox and Hyper-V hypervisor, as well as containerization using Docker, would be a good option.