A Virtual Machine (VM), as the name suggest, is a “Virtual” machine. It is an emulated computer that runs inside a computer program which is used to create, run and manage VMs. Such programs are called Hypervisors. Some of such programs are VirtualBox, Parallels and VM Ware. The VM is often referred to as the guest Operating System (OS) since it runs inside a computer program running on the host OS. Such computer programs like VirtualBox let you decide upon how much computer memory and processing power should be available to the VM. A VM will have access to the actual hardware resources like networking devices, USB Drives, CD/DVD Drives, etc as per the VM settings and policies decided by the system administrators. These VMs work in such a way that the guest OS does not realise that it is working inside a VM and not on an actual computer.
Advantages of using VMs:
- Multiple VMs can be installed on a single computer depending upon availability of hardware resources
- Taking snapshots of a VM at regular intervals will help in recovery of data in case of disaster
- VMs are easy to create, manage and run
- They reduce cost as multiple hardware need not be bought for running separate machines
- It is better than installing multiple OSs on same computer (multi-booting) as it allows running all the OSs parallely whereas in multi-booting only one OS can be run at a time
- VMs of major OSs are readily available for download and can be run immediately after they are downloaded
- They can be used to run an OS on a machine which would be otherwise not easy to run – e.g. Linux on a MacBook
- Insecure applications can be run in a VM to test them out rather than actual OS without the fear of being harmed by the insecure application
Disadvantages of using VMs:
- They are not as fast as a regular computer on same set of hardware since they access the hardware indirectly
- Multiple VMs running on a computer can give unstable performance
For Wikipedia entry on Virtual Machine, click here.
For more posts on Operating Systems, click here.
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