Virtualisation — what it is and is it for me?

There is much talk in the industry at present about virtualisation, however, for many users this is viewed as just the next talking point in a long list of new technologies that will overhaul the IT industry. Unfortunately, these network IT managers who have not yet taken on board the benefits of virtualisation, may be missing out one what could be the biggest changes in the computer and networking industry in the last couple of years.

What is virtualisation?

Virtualisation is fundamentally the ability to run the server applications not on physical machines, but on virtual machines. Sure, the virtual machines themselves run on actual physical hardware, but they are not tied to any particular piece of hardware. Let us imagine a small office environment. In this example we have three servers, one for data, one for email and one for an intranet. Each physical server is running its own server application. Should any one server fail, then that application is not available to all the users. In an attempt to reduce failures, IT managers will therefore provide battery backup for some or all of these servers, but this only protects against brown-outs and power outages, and does not protect against software or hardware failure.

Imagine now that we run one third of each application on each of the three physical machines. This complicates the server software somewhat, but has the advantages that if any one machine fails, then the users still have access to the other two machines running all the applications. From a user experience, throughput and response might be degraded, but overall the systems continue to operate.

Is virtualisation right for me?

As computer hardware continues to increase in performance, with the likes of Intel and AMD constantly increasing the capabilities of the main processors, many of the actual servers being used today are fully capable of being able to be upgrade from physical to virtual machines.

Two key criteria which may need attention are the amount of physical memory and the Network Interface Card (NIC). Having enough physical memory is important, as you do not want the machine constantly having to cache the contents to disk as the CPU is not running multiple applications. The NIC is important as the CPU now has one more additional task to perform in a virtual environment, which is ensuring that data coming in from a high speed Ethernet port is placed in the correct queue for the correct virtual machine. Luckily, specialist NIC cards are available with multiple Gigabit or 10 Gigabit ports, which have an on board processor helping alleviate this task from the main host CPU. In fact, with virtualisation, it is normally possible to reduce the number of actual physical servers, as the physical servers run far more efficiently in a virtualised environment.

Managing Virtual Machines

In reality, it is probably easier to manage a group of virtual machines than it is physical machines. Virtual machines have the advantage that they constantly communicate regarding available resources, such that there is a form of load balancing of the applications across the virtual ‘cloud’. This not only allows the machines to run more efficiently, but ensures that applications do not become constrained by the physical capabilities of one single machine. Management software used to create the virtual machines has the ability to allow applications to be installed, updated or removed from multiple physical servers concurrently, without the need to deal with each physical machine on an individual basis.

Benefits?

The benefits are great when moving to virtualisation, including:

•    More environmentally friendly - By using fewer physical machines, in an efficient manner, fewer machines need to be switched on in the server room. This reduces the amount of energy needed to power the servers, and also, as less heat is produced, requires less power to be used on air conditioning.

•    Lower CAPEX and OPEX costs - Fewer servers reduces the amount of electricity needed to run the servers and to run the air conditioning. In addition, CAPEX can be reduced as in many cases it is possible to run the network without the need of battery backup, as the failure of a single server does not result in the loss of a single application to the users.

•    Simplified Server management reduces the amount of time needed by IT managers to operate, manage, and maintain the servers.

•    Better application loading of the servers results in applications running faster, making users more efficient and more content with the response of the network.