Is Pourqoui the virtualisation of the waiters important?

The lines of business are computerized more and more. We observe a multiplication of the waiters. Waiters which increasingly powerful and under-are often exploited.
This growing number of equipment bring material and financial constraints.

These constraints are in opposition with the present needs for the companies: reduction of the data-processing costs, prevention of the material breakdowns, multiplication of the equipment and easy management of the equipment.

The various evolutions of data processing lead inevitably to modes or tendencies on the management of data processing by the Directions of the Information systems.

It is with a minimum of technical terms that I will present this technology to you, will evoke his uses, his advantages and his rare disadvantages, to finish with a real example quantified on the virtualisation of the waiters of site YAH00 Groupes in 2006.

Advantages of the virtualisation

First of all, Virtualisation makes it possible to optimize the use of the resources. Then, these technologies also make it possible to realize savings on the material thanks to the mutualisation. In the event of need of more than resources, a virtual machine can very simply be moved on a waiter less requested or more powerful. Finally the installation, the deployment and the migration can be facilitated thanks to the use of the virtual machines.

*La mutualisation
The mutualisation is the action to gather several virtual machines on a physical waiter, one leaves the diagram: “An application = a physical waiter”.

This technique makes it possible to reduce the number of physical resources necessary, to simplify the infrastructure network and thus to reduce the budget of investment.

*Réductions of the data-processing costs

The number of waiters and the quantity of computer material necessary in the data center will be reduced. That results in a reduction in the real expenses, requirements in power supply and air-conditioning, involving a clear reduction of the data-processing operating costs.

Following the mutualisation of the resources, it is possible to consider the concentration of the equipment. Indeed, if we have less physical equipment, we need less place to store them. We can then gather them in a single room whereas they were placed in several before. It is necessary to keep in mind that a computer room worthy of this name is a concentrate of technology (Breakdown by the false-floor, protection fire, access control, antiseismic protection).

Daily applications of the virtualisation

For recall, a virtual machine is only one file carried out by an application. On the basis of this principle, nothing is easier than to safeguard it, on various supports, to modify it or to restore it.

*Environnement of test and deployment

It is indeed another asset of the virtualisation. During tests of parameter settings, nothing is easy any more, in some clicks, than to return in an initial state of the virtual machine.
Thus, the teams of validation can devote more time to the phase of test or reproduce the environment of production of their customer.
Easy administration: the various tools of virtualisation are easy to take in hand.

*Security

The virtual waiters “are completely isolated” from the waiter host and other virtual machines. It is thus very easy to delegate tasks of administration on one or more waiters while avoiding an direct access with the physical machine.

* Availability of the resources

We saw previously that a physical machine supports several virtual machines. It is thus natural to wonder about the impact of the stop of a waiter host.
Indeed, if the physical machine breaks down, it is not any more one, but several waiters which stop with more or less important consequences for the data-processing production.
In order to avoid all nuisances of this kind, there exist two solutions:

- The distribution of load
The distribution of load is not resulting from the virtualisation, but functions according to a similar mode, starting from a specialized case.
Let us suppose that the production of the company rests on 2 critical applications laying out each of two waiters. The principle is of course to use a waiter in help in the event of breakdown of the other, but also to distribute the load of a waiter on the other with for objective the maintenance of response time correct and sufficient to ensure the production.
We thus have below 4 physical waiters, which as we saw previously are overall unoccupied (average rate of occupation of the processor: 15%).

By virtualisant these waiters, it is thus possible to plan to set out again the load on 2 or 3 waiters physique.

- The automatic recovery on incident
Virtualisation serves also the prevention of the material breakdowns and the improvement of the recovery plan of activity. Indeed, the virtual equipment being a whole of files, it is easy to safeguard them. In the event of material problem on their waiter host, the files safeguarded before could very quickly be restored on one on another host. It will then be enough to start the virtual machine to take again the activity.

Installation (When? and How?)

1. To estimate its needs for storage

Despite everything the advantages had by the virtualisation, it is necessary to keep in mind that the storage of the images of the virtual machines represents a considerable disk space.
Moreover, let us not forget that it is also necessary to safeguard according to a rate/rhythm defines by 'system administrator, the databases and other applications supported by the virtual machines.
MATERIELTU
The acquisition of a storage unit network (NAS: Surface of network storage: data-processing equipment connected to the network providing the function of data storage) must thus accompany the virtualisation to respect an effective policy of safeguard.

2. To have a powerful network

As evoked in the preceding chapter, it is imperative to have a consequent storage. Now, it is necessary to adapt its architecture network to the quantity of data likely to forward on this network.
At the time of the restoration of an image of virtual machine, the network must be able to continue to offer same quality of service to all the applications.

Indeed, the installation of Virtualisation can requires a recasting of the already existing and pleasing architecture of new security issues. These technologies require additional competences. If there is only one virtual machine per physical machine, the losses of resources compared to the initial system are considerable.

Estimate of the direct and indirect costs of data-processing architecture before and after virtualisation: For YAHOO! (in 2006)
of + 1.5Millions to +700.000$.