1. Context

The amount of electronic data per user (photos, music, videos, etc.) continues to grow. Until now, this data has been stored on the user's computer, but with new modes of access (smartphone, tablet, etc.), users want to be able to access their data wherever they are, and whatever means of access they use. This is known as the "cloud": the user's data (or applications) are hosted in a "cloud", and it's up to the hosting provider to deliver the expected service.

While the term "cloud" deliberately evokes something with a fuzzy outline and few, if any, boundaries for the user, for the hosting provider, on the contrary, it represents something very concrete and very precise. In view of the number of users involved, the margins to be freed up, and the need to rationalize space and power consumption, hosting providers very often opt to implement virtualization. While...