A virtual machine (VM) is an emulation of a physical computer system. VMs run their own operating systems and programs as if they were on a physical machine. This provides benefits like being able to run multiple operating systems simultaneously on one physical system and improved security and application provisioning.
Common Uses of Virtual Machines
There are several common uses and examples of how VMs are leveraged in real-world scenarios:
Development and Testing Environments
Developers can create multiple VMs with different environments for coding and testing applications in a sandboxed space. This makes development more efficient and contained.
Running Multiple Operating Systems
VMs allow multiple operating systems to run simultaneously on a single physical machine. For example, a Windows host system can run Linux and macOS as VMs.
Multiple virtual servers can run on a single physical server leading to better hardware utilization.
Public clouds like AWS and Azure heavily utilize VMs to provide scalable computing resources to customers.
Sales engineers can demonstrate software capabilities on a VM without affecting their main computing environment.
Backup and Disaster Recovery
A VM can be used as a backup instance in case of any physical server failure. VMs can also be replicated across data centers for disaster recovery purposes.
Key Components of a Virtual Machine
There are some key components that make up a standard VM:
Virtual Hard Disks
This is the virtual hard drive space allocated for the VM. It stores the VM’s operating system, programs, and files.
Memory is allocated from the physical machine to the VM. More RAM allows the VM to handle larger workloads.
A virtual network interface allows the VM to access networking resources like connecting to the internet.
The physical CPU cores are shared between VMs running on a system. More cores allow VMs to run applications faster.
Software like VMware and VirtualBox manage and control VMs, allowing the creation and running of VMs.
Creating a New Virtual Machine
Here is an example walkthrough for creating a new VM on a Windows 10 PC:
Step 1 – Install Virtualization Software
VirtualBox or VMware must be installed to create and run the VMs. Both paid and free options are available.
Step 2 – Create New VM
Open the virtualization software and click the “New” button. This launches the VM creation wizard.
Step 3 – Allocate Resources
Select the amount of RAM, virtual hard drive space, and number of CPU cores to allocate for the VM.
Step 4 – Choose OS
Choose the operating system like Linux or Windows that will run on the VM.
Step 5 – Virtual Networking
Configure how the VM will connect to the physical host machine and other systems on the network.
Step 6 – Finish and Run
Complete any other VM settings and launch the new VM!
Benefits of Virtual Machines
There are many benefits to using virtual machines instead of only physical machines:
- Cost Savings: Requires fewer physical server resources to run multiple VMs. This reduces capital and operating costs.
- Isolation: Issues on one VM don’t affect other VMs or the host. Provides security and compartmentalization.
- Quick Provisioning: New VMs can be spun up in minutes without having to procure new hardware.
- Scalability: VMs can be easily scaled up or down to accommodate changes in resource needs.
- Increased Uptime: Downtime is reduced since VMs can be moved from host to host without disruption.
- Environment Consistency: Development and testing environments can mimic production consistently.
- Backups and Recovery: VMs can be backed up, duplicated, and restored easily for disaster recovery.
Virtual Machine Use Case Examples
Some more concrete use case examples of leveraging virtual machines:
A developer needs to test an application on multiple operating systems and browser combinations. They create VMs for Windows, Linux, and macOS with different browser versions without having to reboot their main system.
A company has 10 physical servers, but typical utilization is at 50% capacity. They migrate the servers into 5 VMs on 2 new higher capacity physical servers saving costs.
Legacy Application Support
A company has a critical legacy application that only runs on outdated hardware. They can create a VM that emulates the vintage OS and hardware to keep the app running.
A company can create limited access, temporary VMs for contractors to securely work on projects without accessing the main environment. VMs are deleted after the work is complete.
An online learning company creates VMs preconfigured with the needed software and environments for students. This gives each student sandboxed access to safely learn.
- Virtual machines provide an isolated environment that emulates physical hardware for running operating systems and programs.
- Using virtualization software, VMs allow faster provisioning of systems and the ability to run multiple operating systems on one physical host.
- Benefits include cost savings, quick scaling, easier development and testing, improved uptime and recovery, and increased security.
- VMs are leveraged for web and software development, server consolidation, running legacy apps, providing cloud infrastructure, and delivering training environments.
Virtual machines provide a flexible and efficient way to maximize computing power. VMs allow companies to reduce costs, increase availability, sandbox environments, and speed up operations. With capabilities like live migration and snapshots, VMs create a robust platform for security, testing and development, running multiple operating systems and workloads, and consolidating servers. The power of virtualization will continue to expand as software and hardware capabilities grow.
- What are the disadvantages of using VMs?
Some disadvantages of VMs include:
Increased hardware resources required on hosts
Performance limitations compared to bare metal
Additional software licensing and management
Limitations in migrating some apps to VMs
Potential compatibility issues between OS and underlying platform
- What is virtualization?
Virtualization is technology that allows emulated, virtual environments to be run on physical computing infrastructure. It enables multiple VMs with different operating systems and programs to run on the same physical server.
- What’s the difference between virtualization and cloud computing?
Cloud computing utilizes large-scale virtualization technology and hardware resources to deliver computing services over the internet through data centers owned and operated by providers. Virtualization software can run locally without involving cloud infrastructure.
- What types of virtualization are there?
Some common virtualization types include server virtualization, storage virtualization, network virtualization, desktop virtualization, and application virtualization.
- What is virtual memory?
Virtual memory is a memory management technique that simulates additional memory space by temporarily transferring data from RAM to disk storage. It is a functionality of the operating system, not virtualization technology.
- Can you run Mac OS on a VM?
Yes, Mac OS can be run on supported virtualization platforms like VMware and VirtualBox. However, this is only allowed under Apple’s licensing terms for limited testing and development purposes.
- Is virtualization more secure than bare metal?
Virtualization provides additional security benefits like isolating VMs and data from each other. But it also expands the attack surface since the hypervisor provides a central point of access. Overall security depends on properly hardening and configuring both virtual and physical systems.
- What are examples of hypervisors?
Common hypervisor examples include VMware ESXi, Microsoft Hyper-V, Oracle VirtualBox, and the open-source KVM and Xen hypervisors.
- How does cloud computing use virtualization?
Public cloud platforms leverage large-scale virtualization to provide customers flexible computing capacity through virtualized servers, storage, and networking that is managed by the cloud provider.
- Can you convert a physical server to a VM?
Yes, physical to virtual (P2V) conversions are common to migrate physical servers to VMs. This is done through disk imaging of the source server which is then run on virtualized hardware through a hypervisor.
- What is virtual desktop infrastructure (VDI)?
VDI delivers virtualized desktop environments hosted on servers in a data center which are then accessed remotely by users through thin clients or other devices. It separates the desktop OS and apps from the physical device.
- What are the technical requirements to run virtual machines?
Key VM technical requirements include compatible 64-bit CPU with virtualization support, adequate RAM and storage, virtualization software like hypervisors, and hardware virtualization support in the BIOS enabled.
- Can you run Windows on a Mac using VMs?
Yes, Parallels and VMware Fusion enable running Windows on MacOS hosts. The Windows VM runs isolated from the host Mac OS. This allows using Windows apps and tools on Mac machines.
- How do you access a VM?
Users interact with a VM similarly to a physical computer. You can connect a display, keyboard, mouse, and network connection to the VM. Additional remote access options are available like Remote Desktop Protocol and VDI clients.
- How are resources allocated to VMs?
Virtualization software allows configuring fixed amounts or dynamic shares of host resources like CPU cores, RAM, and disk space to be allocated to each VM. This provides predictable performance and isolation.
- What is virtual networking?
Virtual networking creates software-based network connections between VMs, between VMs and hosts, and between VMs and external networks. This allows VMs to communicate like physical systems connected to a traditional network.
- Can you increase RAM on a virtual machine?
Yes, the amount of RAM allocated to a VM can be increased after initial configuration based on changing workload demands. The total RAM available is constrained by the physical host system’s actual memory.
- What is a virtual private network (VPN)? How is this different from virtualization?
VPN is used to extend private networks over public ones like the internet. It encrypts traffic and tunnels it through an intermediary network. Virtualization is technology to emulate hardware environments, not networking.
- What is live migration of virtual machines?
Live migration moves a running VM from one host to another without disruption for users or loss of service. Memory, storage, and network connectivity are transferred while the VM continues operating.
- Can you run any operating system on a VM?
Most common operating systems like Windows, Linux, and macOS can run on VMs. But some proprietary OSes are restricted by vendors from virtualized deployment, or have limited functionality.