What VM means?

VM stands for Virtual Machine. A virtual machine (VM) is a software-based computer system emulation that behaves like an actual physical computer from the perspective of the end user. It runs its own operating system, applications and workloads by virtually sharing underlying physical hardware resources allocated to it by a hypervisor.

VMs allow creating multiple isolated portable compute instances in software-defined form factors. They constitute foundational elements enabling infrastructure virtualization.

What VM means?

Overview of Virtual Machines

A virtual machine is a virtualized compute environment that mimics a physical computer system. Key properties:

  • Runs a complete operating system and apps like a physical computer.
  • Shares resources of underlying host hardware allocated by hypervisor.
  • Remains functionally isolated from host and other VMs.
  • Exists as software image independent of hardware.
  • Can start, stop, reboot independently just like physical computers.

So in essence, VMs are logical representations of physical computer systems instantiated purely in software.

What Does VM Stand for in Virtual Machine?

In the term ‘virtual machine’, VM stands for following key aspects:

Virtual

Exists in software form created logically through virtualization without actual real-world physical analog.

Machine

Mimics the functioning of a real computer system in aspects like CPU, memory, network, storage etc.

So ‘Virtual Machine’ refers to emulated computer systems brought to life virtually using software abstraction without concrete physical hardware.

Key Functions of a Virtual Machine

The core functions of a VM include:

  • Encapsulates entire workloads – OS, apps, libraries etc.
  • Achieves portability across physical hosts since embodied in software.
  • Attains compute performance through fine-tuned resource allocation.
  • Provides isolated environments for running processes securely.
  • Simulates customizable virtual hardware environment.
  • Supports different guest operating systems.
  • Enables backup, recovery and live migration of entire workloads.

So VMs enable deployment flexibility along with mobility and encapsulation.

How Does a Virtual Machine Work?

A virtual machine works based on the following principles:

  • A hypervisor creates virtualization layer between host hardware and VMs.
  • The hypervisor allocates isolated share of physical resources – CPU, RAM, storage, network to each VM.
  • A guest OS is installed within the VM utilizing the allocated resources.
  • Apps execute within the guest OS using simulated virtual hardware.
  • The guest OS and apps remain agnostic to actual underlying hardware.
  • VMs function as self-contained execution sandboxes isolated from hosts.

So the VM architecture enabled by hypervisor provides a portable virtual hardware environment to guest machine workloads in a transparent manner.

Comparison – Physical Machine vs Virtual Machine

Physical Machine Virtual Machine
Made up of discrete hardware components like CPU, memory, disks assembled together. Created logically in software without concrete hardware.
Resources like CPU, RAM, storage physically present. Resources emulated virtually through hypervisor allocation.
OS installation ties software to hardware. OS encapsulated with workload decoupled from hardware.
Mobility limited based on physical relocation. Portable between hosts since software-defined.
Direct access to underlying hardware resources. Access indirectly via hypervisor abstraction layer.
Fault tolerance requires standby systems. Live migration across hosts minimizes downtime.
Upgrading requires new hardware procurement. VM configuration like memory can be changed dynamically.
Hardware dictates scalability potential. Can be provisioned instantly without procurement delays.
Physical space and energy consumption constraints. Higher density consolidation with reduced power needs.

So virtual machines offer greater flexibility, mobility and efficiency over physical server systems.

Type 1 vs Type 2 Hypervisors for Virtual Machines

Hypervisors create the virtualization layer required for spawning virtual machines. There are two types:

Type 1 Hypervisors

  • Also known as bare-metal or native hypervisors.
  • Run directly on host system hardware with no intermediary operating system.
  • Examples – VMware ESXi, Microsoft Hyper-V, Xen, Oracle VM.

Type 2 Hypervisors

  • Also known as hosted hypervisors.
  • Run as software layer on top of traditional operating system.
  • Examples – Oracle VirtualBox, Parallels Desktop, VMware Workstation.

So Type 1 hypervisors provide higher performance for enterprise VMs while Type 2 suits local small-scale usage.

Virtual Machines vs Containers

Though both provide virtual operating environments, key differences exist between VMs and containers:

Virtual Machines Containers
Emulate hardware, run full machine images with discrete OS. Share host machine OS kernel, bin and libs. OS virtualized instead of hardware.
Heavier footprint due to full OS image. Slower boot up. Lightweight as leverage existing OS. Faster startup.
Hypervisor provides encapsulation and isolation. Uses native OS process isolation. Additional software adds management capabilities.
Each VM runs its own dedicated OS instance. Multiple isolated containers share same host OS.
Full isolation and security out of the box. Need tweaking host OS settings for equivalent isolation as VMs.
Hardware-level virtualization suited for scalability and resilience. Quick deployment of apps in standardized environments across stacks.

So VMs provide full system virtualization while containers offer application-centric isolation models.

Virtualization Requirements for Virtual Machines

Following key requirements must be met for creating performant virtual machines:

Hypervisor Software

Hypervisors like VMware ESXi, Hyper-V, Xen etc. create the virtualization layer to instantiate VMs and allocate host resources.

Hardware-Assisted Virtualization

Hardware capabilities like Intel VT-x and AMD-V allow CPUs to efficiently run guest OSs inside VMs.

OS Support

Guest OS must support integration drivers and APIs to offload I/O handling for performance.

Hardware Compatibility

Server hardware must be certified compatible for virtualization through BIOS settings like CPU VT enabled.

Sufficient Resources

Appropriately specced server infrastructure to offer required compute resources to VMs in a non-overcommitted manner.

So a combination of compatible hardware, hypervisor software and OS support creates optimal foundations.

Key Benefits of Virtual Machines

Significant benefits provided by virtual machines:

Hardware Independence

Ability to run workloads detached from underlying physical servers. Enables mobility.

Isolated Environments

Workloads execute securely in isolated VMs mitigating compatibility issues.

Server Consolidation

Multiple VMs can co-exist on same server driving up asset utilization.

Rapid Provisioning

VMs created instantly without lead time compared to procuring physical servers.

Improved Continuity

Live migration, failover clustering, instant recovery options limit application downtime.

Better Scalability

Scale capacity up or down dynamically by provisioning additional VMs on demand.

Cost Savings

Reduced expenses on space, cooling and electricity from higher asset utilization and smaller hardware footprint.

So VMs deliver agility, continuity and efficiency.

Key Takeaways

  • Virtual machine refers to emulated computer system instantiated based on software virtualization.
  • Hypervisor allocates logical share of host physical resources to each VM created.
  • Entire workloads encapsulated and decoupled from underlying hardware.
  • VMs offer encapsulation, portability and hardware independence to workloads.
  • Enable server consolidation, rapid provisioning and service continuity gains.

Conclusion

The advent of virtual machines revolutionized computing by detaching entire software workloads from tight hardware coupling and constraints. This enabled unprecedented flexibility in how systems are deployed, managed and consumed while driving better asset utilization. By establishing a virtualization layer, multi-tenant VMs can securely share underlying host resources in an isolated manner managed by the hypervisor. The software-defined and portable nature of VMs unlocked immense potential for reliability, scalability and efficiency. Virtual machines continue to drive innovation in computing models like cloud and edge by simplifying delivery of IT infrastructure on demand. Their encapsulation capabilities catalyzed technological breakthroughs enabling the virtual enterprise.

FAQs

  1. Can multiple VMs run on the same physical server?
    Yes, through virtualization multiple virtual machines can efficiently share the underlying physical resources of the same server on which they run.
  2. Do VMs require a hypervisor?
    Yes, a hypervisor is required to create the virtualization layer enabling instantiation and runnning of virtual machines by managing host physical resources.
  3. Are VMs hardware or software?
    Virtual machines are software implementations of computing environments. The physical hardware is abstracted using the hypervisor and only virtual resources are presented.
  4. Are VMs completely isolated?
    Yes, well-designed hypervisors completely isolate VM processes from each other and underlying hosts to prevent data leakage across virtual machine boundaries.
  5. Can a VM run without a host system?
    No, VMs cannot run independently without an underlying host providing the physical resources. The hypervisor binds them to the host.
  6. Can I move a VM to a different host system?
    Yes, a key benefit of VMs is live migration capabilities allowing seamless transfer of running VMs across underlying host systems without disruption.
  7. Do VMs increase resource utilization?
    Yes, by enabling multiple VMs to share host resources, overall asset utilization is increased through consolidation, improving efficiency.
  8. Is a VM slower than a physical system?
    A properly configured VM has minimal performance overhead usually less than 5% compared to native physical system while delivering flexibility benefits.
  9. How is a VM created?
    VMs are created by hypervisor software based on configurations set by admins for parameters like vCPUs, memory, network, storage etc. along with the guest OS template.
  10. Can I mix VMs running different operating systems?
    Yes, one of the benefits of VMs is ability to run different guest OSs like Windows, Linux, Netware in VMs on the same physical host system thanks to isolation.
  11. Can VMs improve disaster recovery ability?
    Yes, portability and live migration capabilities coupled with instant failovers to replicated VMs across sites greatly enhances disaster recovery flexibility.
  12. Is VMware required for creating VMs?
    No, while VMware is a market leader, virtual machines can also be created using hypervisors like Hyper-V, VirtualBox, Xen, KVM etc. from other vendors.
  13. Are VMs suitable for high performance needs?
    Yes, current generation hypervisors have very low overhead so properly architected VMs can deliver high performance that matches and scales as well as physical systems.
  14. When are containers better than VMs?
    Containers are faster and lighter than VMs. They suit apps with portable runtimes like PHP, Python etc. needing standardized environments vs VMs appropriate for monoliths.
  15. How does live migration work for VMs?
    Hypervisors like vSphere VMotion enable live migration by copying execution state of a running VM between hosts while keeping applications online during short switchover.
  16. Can VMs improve availability?
    Yes, capabilities like live migration, rapid scaling, instant restarts and failover clustering enabled using VMs significantly boost availability and reduce application downtime.
  17. Is Windows or Linux more suitable for VMs?
    Both Windows and Linux function very well within virtual machines. Linux has smaller footprint so can run more VMs per host. Windows dominates business apps space requiring VMs.
  18. How are resources allocated to VMs?
    Hypervisor allows allocating dedicated virtual resources like vCPUs, vRAM, vNICs, vDisks to individual VMs in a customized yet isolated manner from the physical host resources.
  19. Do VMs work on any x86 server?
    VMs have processor requirements and also need hardware-assisted virtualization support for optimal performance. Only certified servers provide full compatibility.
  20. Can I run VMs on my laptop?
    Yes, desktop hypervisors like VMware Workstation and Oracle VirtualBox allow easily running multiple VMs locally on notebook and desktop systems.

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