You have probably heard more than once that the “virtual machines” and, if you are reading this text, chances are you’re not sure what exactly. Do not be fooled by its mysterious name, because although its internal operation is very complex, the concept itself is simple and you use them every day.
A virtual machine is nothing more than software capable of carrying inside another operating system into thinking it is a real PC. As its name suggests, the concept is as simple as creating a machine (PC, console, mobile or whatever) instead of being physical is virtual or emulated.
What is a virtual machine?
Once it has become clear that a virtual machine is not any machine full of gears with a virtual reality helmet, but software, let’s get more detail about what are the virtual machines.
The first thing to know is that there are two types of virtual machines differentiated by their functionality: the system and process, although the vast majority of the time you hear talk about an almost certain virtual machine that will be referring to those systems.
System virtual machines
A virtual machine system is one that emulates a full computer. In plain words, it is software that can impersonate another device – like a PC- so you can run another operating system inside. Has its own hard disk, memory, graphics card and other hardware components, although they are all virtual.
That their components are virtual does not necessarily mean they do not exist. For example, a virtual machine can have some resources reserved 2GB of RAM and 20 GB hard drive, which obviously come from somewhere: the PC where the virtual machine, also sometimes called the hypervisor is installed, the host or host . Other devices could actually be physically existing, such as a CD-ROM that really is the content of an ISO image instead of a CD of truth.
For the operating system running inside the virtual machine all this emulation is transparent and invisible. Everything works the same as if it were running on a normal PC, without knowing who really is tucked inside a bubble inside another operating system. In fact, nothing prevents you from doing like in the movie Inception / Origin and creates another virtual machine within the previous virtual machine.
In his bubble, the virtual machine cannot access the other host machine data despite being physically running on the same, they are isolated. However, the main applications of virtual machine like VirtualBox or VMWare have shortcuts and tools to facilitate the task of moving files from one machine to another.
To run a virtual machine maps the virtual devices offered his guest with the actual devices on the physical machine. For example, the machine can be emulating a sound card Sound Blaster 16-bit, although in truth it is connected to the internal sound card motherboard of your laptop that is Realtek.
Virtualization software can be by or support by hardware, in which case a better yield is obtained. Since 2005 it is common with technology processors have hardware virtualization, although not always enabled by default in the BIOS.
Process virtual machines
A virtual machine process is less ambitious than one system. Rather than emulate a PC completely, run a specific process, as an application, in its runtime environment. It sounds esoteric, but use it every time you run an application based on Java or .NET Framework – based.
This is useful when developing applications for multiple platforms, because instead of having to program specifically for each system, the execution environment (i.e. the virtual machine) is in charge of dealing with the operating system.
Process virtual machines allow you to enjoy applications that behave identically on different platforms such as Windows, Mac or Linux, but you as a user normally not lend much attention. So, unless you’re a programmer, usually when it comes to virtual machines we are referring to the system.
What virtual machines are used?
All this is fine, but why would anyone want to create a virtual PC inside your PC? While this entry might seem a rather trivial idea, really it is that virtual machines have a variety of utilities in the professional environment and the final consumer. These are the main uses:
- To try other operating systems: Install an operating system on your PC is a long, tedious and difficult to reverse if you are not satisfied with the results process. So when there is a new version of Windows it is easier and safer to try installing it in a virtual machine on your hard drive. If something goes wrong, the noils and over, without risking losing much time or your data.
- To run old programs: What happens when your business depends on software that is not updated for 20 years? If you cannot upgrade the software you no choice but to keep carrying him on an operating system of its time. With a virtual machine this old system can run on existing hardware rather than on a PC scrap. The same can be applied to older games that have stopped working on modern hardware or software.
- To use applications available for other systems: You may also need a virtual machine to run applications that have been developed for a different operating system you are using. For example, to use an application to Linux from Windows, or vice versa.
- To test an application in different systems: As an application developer you are interested to work properly in as many possible configurations, and that includes different versions of operating systems. One option is to have half adozen PC installed with different versions of Windows … or just one virtual machine for each version.
- As additional security: Being isolated from the rest, a virtual machine gives you extra security in precise tasks that you want to be sure that an application will not have access to the rest of your data. That’s why they are often used to install as dangerous as viruses and malware to study things.
- To take advantage of its great dynamism: By its nature virtual machines are very useful in cases where you need a dynamic end in the system. You can save states (exact copies of your data), zoom, move them to a completely different hardware and continue running smoothly. Therefore, they are indispensable for example in companies with web servers that host a multitude of machines with web sites of its customers.
All these applications come with a major drawback: the performance. As expected, if the hardware of your PC is used to move two operating systems at once instead of one, performance suffers. Moreover, although more applications to create virtual machines are more efficient and more powerful hardware, emulating a system always it requires extra effort that is not necessary if the software could communicate directly with the hardware, without intermediaries.
How a virtual machine is used
To use a virtual machine the first thing you need is to install an application on your PC able to create it or at least play it. There are several well – known applications capable of doing this, but the most famous are VMWare, VirtualBox, QEMU and Parallels.
The importance of a virtual machine to ensure the operation of old software is such that Microsoft has launched over the years several programs for Windows for this purpose. In the case of Virtual PC, Windows XP Mode or the new HyperV.
For its open source nature, great compatibility with many hosts and guest operating systems, we will focus on VirtualBox, but probably get similar results with other programs.
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Virtual machine applications are usually pulling heavy, and VirtualBox is no exception. From the download page choose the one that corresponds to your operating system and system architecture and download it. The file is just over 100 MB.
Installation is not complicated, but some of the windows of options can make you doubt wondering what you want or do not want to install components. The solution is simple: I leave everything as it is enabled and click Next.
Do not worry, VirtualBox is a legit application and installer does not include any nasty surprises. The only thing you have to consider is that at a time of installing your Internet connection is lost for a few seconds to install the virtual network. The installation itself notifies you before this happens.
During installation, you may be prompted for confirmation to install drivers for different virtual devices. Again, do not panic, everything is normal and necessary. You accept.
Soon there will be completed the installation. Congratulations, you have everything you need to start using your virtual machine.
Create a virtual machine
To start playing God with your PC and create virtual worlds you have two options: either create a virtual machine from scratch or import an already created. The most common is you want to start from scratch, as it is more common to have an ISO image with the operating system that a complete picture of virtual hard disk.
Click the New button to start creating. In the first step, you must choose the operating system that you plan to install. I in my tests and for the sake of science and retro will install Windows 3.1 on my virtual machine.
In the following steps in the wizard, you specify how many resources of your PC going to allocate to the virtual machine. First, you ask for the RAM, where you must choose a balanced courage not to drown your main operating system. For Windows 3.1 I have no problem (official requirements are 2MB of RAM), but if you’re installing something more current as Windows 10 you should assign at least 1 GB of RAM.
The next step is a bit more complicated: the virtual hard disk. Virtual hard disks can be reused in a virtual machine to another, or import hard disks already created in almost any possible format (VHD, VMDK, HDD …) Most often, you want to create a new one, in which case you are asked you choose a format and size.
The preset choices are correct in most cases. Although reserved option is selected dynamically, you still need to choose a fixed size in the next window. The difference is that if you choose fixed size, the maximum size is always busy on your host PC (although in the virtual machine is empty).
Again, it depends on what system you’re installing for that you need more or less space on the virtual hard disk. Keep in mind not only what occupies the operating system, but any other application you are going to install, temporary files and user files. Better than on a bit missing, do not let the guest system asphyxiated without space.
After this virtual … Well, more or less machine is created. All we’ve created is the environment in order to install certain operating system, but as such there is nothing inside … yet.
Connect the ISO installation
The most common way to install an operating system on a virtual machine method is to simulate an installation CD by ISO disc images. If you have an actual installation DVD, you can also use.
The first thing to do is mount the installation CD or DVD in your newly created virtual machine. To do this, select and choose Settings. Here you will find many points with which you can play later to tune system emulation, but for now just go to Storage.
Here VirtualBox should have already prepared a CD, DVD or floppy drive depending on which operating system and virtual machine version is based. In any case, the operation is the same: select the device and click on the icon next to your name to load the disk image you want to ride instead. In my case I have three disk images to install MS-DOS first, so I mounted the first.
Now it’s time to start for the first time the virtual machine.
And it is ready now to install …
Return to the main VirtualBox window and press Start to start the magic. If all goes well, the process of installing the operating system that you mounted the CD, DVD, USB or floppy drive, and from that moment you just need to follow the onscreen instructions will be charged.
From the bottom bar of the window you have shortcuts to quickly change various options related to emulation. For example, by right clicking on the icon I can change the floppy disk image to continue installing MS-DOS.
One thing to bear in mind is the capture of keyboard and mouse. When you move the mouse or write with the keyboard inside the virtual machine, VirtualBox captures the keyboard and mouse to send it to the virtual machine and not your normal PC. This is fine, but it can make you stay “locked” inside the virtual machine without being able to return to your PC. For example, if you press Alt + Tab does in the virtual machine and not on your PC.
For that there is the key to escape capture, that have changed unless the key is usually Control on the right of your keyboard. At the bottom of the window indicates VirtualBox you anyway. With you press that key goeth the keyboard and mouse to the host PC.
Another interesting option of virtual machines that can save the state as such, and the next time you continue using it , without having to wait for Windows closes or the like. To do this, all you have to do is choose Save state when prompted to close the virtual machine.
Another option that you can be of great interest are the snapshots. If you have installed an operating system and you have configured and left all precious, why take the risk of this harmony is lost after installing applications? A snapshot is a copy of the state of a virtual machine that can retrieve at any time.
Thus, you can create a snapshot of Windows fully installed and then open a malicious virus that corrupts all your files. The files are corrupted and erased, yes, but can recover the snapshot that will leave everything as it was at the time in which you created. In VirtualBox snapshots (also called snapshots) are a bit hidden, to the right of the window.
As you see, really it is not complicated to create and use a virtual machine. Of course, there are more complex options in configuring VirtualBox and VM itself, but in most cases you need not touch anything else to use an operating system within another, which as we have seen, has a lot of interesting applications.