What is Virtualization?

KVM stands for Kernel-based Virtual Machine. It’s a type of virtualization technology that allows you to run multiple guests on a single hardware host.

KVM is built into the Linux kernel machine.

A number of guests operating system can run on a host including Windows, Linux, and many more.

There are many benefits of virtualization including:

  • Efficient use of hardware resources
  • Ease of upgrading hard drive disk space
  • Ease of upgrading RAM
  • Ease of upgrading CPU
  • Migration of operating system and software to another system, e.g. moving operating systems and applications software from one data centre to another
  • Failover
  • Snapshops

Let’s unpack some of these benefits.

Efficient Use of Hardware Resouces

When you run a data centre and you have 100s of machine performing operations, it’s highly improbable that all the servers will be consuming all of it’s available resources. By virtualizing the servers you are able to more even spread the load and also dynamically upgrade and downgrade as demand goes up and down.

Ease of Upgrading Hard Drive Disk Space

We’ve all faced that dreaded moment when a server’s hard disk space runs out. The mere thought of taking the machine offline, adding a new disk, and finding some way to get the OS to recognize the new disk can even leave an experienced admin shivering. The beauty of virtualization means that you don’t physically have to open the machine. If the system is hooked up to a NAS or a SAN, you can simply add more disk space. This means that your hard drive space is almost use in the most efficient manner. For us at Vander.host, this is probably one of the biggest benefits of virtual hosts versus physical hosts. This can even be done online without having to take the machine down.

Ease of Upgrading RAM

Memory can be easily upgraded if you’re running a virtual machine. No more opening of the hardware box, trying to figure out what speed RAM the machine has, and hoping that it’s still supported in the market. With a VM you can simply shut down the machine, add more virtual RAM, and start it up again. This can take less than 3 minutes depending on your OS startup time.

Ease of Upgrading CPU

CPUs don’t start off working hard. But as the workload increases, the CPU cycles required do too. The magic of virtualization means that when you’re running your CPU starts to struggle, you can simply add more virtual CPUs and see an immediately increase in performance.

Migration of Operating System and Software to Another System

We’ve all faced this before. Some fancy server that has been running for years needs to be migrated to a new physical location. The mere thought of shutting down the old machine, and hoping that it will come back, leaves many an administrator wishing for a long holiday. However if you’re working in a virtual environment, there is something called live migration which allows you to move your virtual machines from one physical host, to another host, even without any downtime.


Most virtualization technologies have advanced failover built-in. A common one is called “High Availability”, or HA is it’s called in the VMWare space. With “high availability” hardware hosts can be linked into a system whereby if the one fails, the other one automatically take over. The failover time is typically just the amount of time it take for a VM to start up.


Snapshots is a very simple way to quickly create an entire replica of a disk. Even if a disk has 100 of gigs in use, the snapshot is created very quickly. Snapshots are an excellent way of creating instant backup and time based replicas of machines.

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