What is a Virtual Machine? | VMware Glossary (2024)

Users can choose from two different types of virtual machines—processVMsand system VMs:

Aprocess virtual machineallowsa single process to run as an application on a host machine, providinga platform-independent programming environmentbymaskingthe information of the underlying hardware or operating system.An example of a process VM is the Java Virtual Machine, which enables any operating system torun Java applications as if they were native to thatsystem.

Asystem virtual machineisfully virtualizedtosubstitute for a physical machine.A system platform supportsthe sharing of a host computer’s physical resources between multiple virtual machines, eachrunning its own copy of the operating system.This virtualization processrelies onahypervisor, which can run on bare hardware, such asVMwareESXi,or on top of an operating system.

All the components of a traditionaldata centeror IT infrastructurecan be virtualized today, with variousspecific types of virtualization:

• Hardware virtualization:When virtualizinghardware, virtual versions of computers and operating systems(VMs)are created and consolidated into a single, primary,physical server.Ahypervisorcommunicatesdirectlywith a physical server’s disk space and CPUto manage the VMs.Hardware virtualization, which is also known as server virtualization,allows hardware resources to be utilized moreefficiently and for one machine tosimultaneouslyrun different operating systems.
• Softwarevirtualization:Software virtualizationcreates a computer system complete with hardware thatallowsone or moreguest operating systemsto runon a physical host machine.Forexample,Android OScan runon a host machinethat isnatively using a Microsoft Windows OS, utilizing the same hardwareasthe host machine does.Additionally,applicationscanbe virtualizedand deliveredfrom a server toanend user’s device, such as a laptop or smartphone. Thisallowsemployees to accesscentrally hostedapplications when working remotely.
• Storage virtualization:Storage can be virtualized by consolidating multiple physical storage devicestoappear as a single storage device.Benefits includeincreased performance and speed,load balancing andreduced costs. Storage virtualizationalsohelps with disaster recovery planning, asvirtual storage data can beduplicatedandquicklytransferred to another location, reducing downtime.
• Network virtualization:Multiple sub-networks can be created on the same physical network bycombiningequipment into a single, software-basedvirtual networkresource.Network virtualization alsodivides available bandwidth into multiple, independent channels, each of which can be assigned to servers and devices in real time.Advantagesinclude increased reliability,network speed,security and better monitoringofdata usage.Network virtualization can be a good choice for companies with ahigh volume ofuserswho need accessat all times.
• Desktop virtualization:Thiscommontype ofvirtualization separates the desktop environment from the physical device andstoresadesktop on a remote server, allowing usersto accesstheirdesktopsfromanywhere on any device.In addition toeasyaccessibility,benefits of virtual desktops includebetter data security,costsavingson software licensesand updates,andease of management.
  

Like virtual machines, containertechnologysuch asKubernetesissimilar in the sense ofrunning isolated applications on a single platform.While virtual machinesvirtualizethehardwarelayer to create a “computer,”containerspackage up just asingleapp along with its dependencies.Virtual machines areoftenmanaged by a hypervisor,whereascontainer systems providesharedoperating system services from the underlying host and isolate the applications using virtual-memory hardware.

A key benefit of containersis that theyhave less overhead compared to virtual machines. Containersincludeonlythe binaries, librariesandother required dependencies, andthe application.Containersthat areon the same host share the same operating systemkernel, making containersmuchsmaller than virtual machines.As a result,containersboot faster,maximize server resources,andmakedeliveringapplicationseasier.Containershave becomepopluarforuse casessuchasweb applications,DevOpstesting, microservices and maximizing the number of apps that can be deployed per server.

Virtual machinesare larger andslower tobootthan containers. They arelogically isolated from one another,with their ownoperating systemkernel, and offer thebenefits of acompletely separateoperating system.Virtual machinesare best forrunning multiple applications together, monolithic applications, isolation between apps, and for legacy apps running on older operating systems.Containers and virtual machines may also be used together.

Virtual machines can be simple to set up, and there are many guides online that walkusersthrough the process. VMware offersone suchusefulvirtual machine set-up guide.