Virtualization is increasingly used by businesses, but it's also used by individuals.
But concretely, why use the virtualization and what does it consist of ?
Originally, virtualization consisted of running a virtual machine on a host machine (as well as a desktop computer, a laptop or a professional server).
For this to be secure, the virtual machine is obviously isolated from the host system. This means that you will not be able, by default, to access the host PC from the virtual machine.
Then, you will see that there is also virtualization of applications. But, we'll see that later.
It's nice to talk about virtual machines, but what is it ?
For the average user, it's the equivalent of a physical machine, except that it is managed in software by a hypervisor (a virtualization software) such as VirtualBox or VMware Workstation.
Currently, virtualization softwares are so sophisticated, it's possible to virtualize many things (such as virtual hard disks, USB controllers, network cards, ....).
Depending on the virtualization software you use, you can even add many virtual devices :
You can even change the version of its USB controller (but, you will need to install an additional driver if the guest OS doesn't support it by default).
As the name suggests, a VPS (or Virtual Private Server) is a private virtual server.
In other words, a virtual machine running on a physical server of a host (such as: OVH, 1 & 1 or LWS).
Of course, to manage these virtual servers, businesses (OVH and others) will not use VirtualBox, but rather hypervisors (virtualization servers, such as Citrix XenServer or VMware ESXi).
When you create a virtual machine, virtually, it will have at least :
When creating a virtual machine, you can also allocate a specific amount of RAM and a number of hearts for its virtual processor.
In summary, the host machine is your PC or physical server.
It's on this PC that you will install the virtualization software (for example : VirtualBox or VMware Workstation).
Then, once the virtual machine is created, you will see that some files have been created on your hard disk.
The host PC is your computer or physical server.
So, the host operating system (or host OS) is the operating system installed on your physical computer.
For the guest OS, it's the operating system installed in the virtual machine.
To use a virtualization software (such as VirtualBox or others), it's very important to have a processor that supports the processor virtualization (Intel VT-x / AMD-V) and then activate it in the BIOS of your motherboard.
If you can, opt for a processor that supports "Intel VT-x / AMD-V" AND the I/O virtualization "Intel VT-d / IOMMU".
Note : don't forget to activate it in the BIOS of your motherboard.
This will protect your host PC from direct memory access attacks by malicious software running in your virtual machine.
In addition, this feature is required to use Windows virtual machines on the Citrix XenServer virtualization server. Without this feature, it will not work.
For more information about the IOMMU or Intel VT-d, refer to our tutorial : Citrix XenServer - PCI passthrough
Any recent processor supports 64 bits, but this is obviously necessary to run 64-bit guest operating systems.
Since a virtual machine acts like a physical machine, it also needs system resources to function.
The system resources to run a virtual machine with Linux as guest OS are obviously not the same as for a virtual machine with Windows as guest OS.
Depending on your needs, you may need :
In short, the more powerful your PC will be, more you can create virtual machines and they will be performing.
Personally, I am a fan of virtualization, especially since I discovered virtualization and system administration.
To test different virtualization solutions (such as VMware ESXi, Citrix XenServer, Citrix XenApp, ...), I had to buy much more powerful hardware to run everything on a single computer.
Currently, in April 2018, I have a pretty good PC with :
First, the choice of the Asus brand is simply linked to the fact that it's a very good brand of motherboard.
While the price is more expensive than other brands (Gigabyte, for example, because low-cost), but it provides a better stability and many features in its BIOS.
Notably, the activation of Intel VT-x and Intel VT-d that are supported by our processor.
Another reason was the presence of an Intel's integrated RAID controller, which is unfortunately not as good as a real RAID controller. Hence the subsequent purchase of this RAID controller : Adaptec RAID 6405.
As mentioned before, there are 2 important features to have when you want to get started in virtualization :
First, since each machine will use at least a few GB of RAM (except for Linux), these 32 GB allow me to run multiple virtual machines at the same time without saturating the RAM of the physical PC.
The other reason is that to virtualize the virtualization servers (like VMware ESXi or Citrix XenServer), I have to allocate about 10GB of RAM to run virtual machines in these virtualization servers virtualized themselves with VMware Workstation or VirtualBox.
In the business environment, RAID controllers are used for two reasons :
For more information on RAID controllers, refer to our articles about Adaptec RAID and Adaptec SmartRAID controllers.
Note that Adaptec RAID is a true RAID, unlike Intel RAID which is a pseudo-hardware RAID and is therefore less efficient than an Adaptec RAID.
Virtualization has advantages, but also disadvantages.
Virtualization has many benefits for individuals :
But also for professionals :
As with any technology, there are also disadvantages, including :
Although virtualization really allows a lot of things, with the right hardware, it also has its limitations.
Indeed, there are some programs or software solutions that don't work in virtual a virtual environment.
For example, you can't, in theory :
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