Method for the assignation of virtual machines hosting applications (λ) to servers of a plurality of servers (μ,v) in a data or calculation centre, to consolidate said virtual machines, at each time instant said plurality of servers (μ,v) being subdivided in a subset of active servers (μ), each hosting a certain number of virtual machines, and a subset of inactive servers (v), the method being characterised in that it utilises a central manager (ξ) of the data centre and a plurality of local managers in a number corresponding to that of the servers of said plurality of servers (μ,v), and in that the following subsequent steps are executed for a new virtual machine to be assigned: S0. said central manager (ξ) broadcasts a request of availability to host said new virtual machine to one or more local managers hosted by a respective number of active servers of said subset of active servers (μ), S1. for each of said one or more local managers, carrying out individually a true/false Bernoulli trial on the basis of the values assumed by a probability function thatoutputs values between 0 and 1 depending on a value of CPU use of a respective active server, wherein: - the probability function outputs a value that vanishes for a CPU use that is smaller than a first pre-defined threshold; - the probability function outputs a value between 0 and 1 with a maximum value equal to 1 and excluding 0, for intermediate values of CPU use; and - the probability function vanishes for values of CPU use higher than a second pre-defined threshold, the second-pre-defined threshold being larger than the first pre-defined threshold; S2. for each of said one or more local managers, declaring availability to accept the assignation of said new virtual machine when the result of the Bernoulli trial in step S1 is true and no availability to accept the assignation of said new virtual machine when the result of the Bernoulli trial in step S1 is false, S3. for said central manager (ξ), constructing a list of available servers on the basis of the availability of each one of said number of local managers given in step S2; and in that, when there is a virtual machine to be assigned to a server, said central manager (ξ): S4. if said list of available servers contain at least an element, chooses, among the elements of said list, the server to which said new virtual machine is to be assigned, and assigns the latter to the former; S5. if said list of available servers does not contain any element, activates a server in said subset of inactive servers (v) and assigns to it said virtual machine to be assigned, wherein if at a given time a local manager does not have any virtual machine running on relevant local server, the latter de-activates and switches off and is therefore included in the subset of inactive servers (v). S0. said central manager (ξ) broadcasts a request of availability to host said new virtual machine to one or more local managers hosted by a respective number of active servers of said subset of active servers (μ), S1. for each of said one or more local managers, carrying out individually a true/false Bernoulli trial on the basis of the values assumed by a probability function thatoutputs values between 0 and 1 depending on a value of CPU use of a respective active server, wherein: - the probability function outputs a value that vanishes for a CPU use that is smaller than a first pre-defined threshold; - the probability function outputs a value between 0 and 1 with a maximum value equal to 1 and excluding 0, for intermediate values of CPU use; and - the probability function vanishes for values of CPU use higher than a second pre-defined threshold, the second-pre-defined threshold being larger than the first pre-defined threshold; - the probability function outputs a value that vanishes for a CPU use that is smaller than a first pre-defined threshold; - the probability function outputs a value between 0 and 1 with a maximum value equal to 1 and excluding 0, for intermediate values of CPU use; and - the probability function vanishes for values of CPU use higher than a second pre-defined threshold, the second-pre-defined threshold being larger than the first pre-defined threshold; S2. for each of said one or more local managers, declaring availability to accept the assignation of said new virtual machine when the result of the Bernoulli trial in step S1 is true and no availability to accept the assignation of said new virtual machine when the result of the Bernoulli trial in step S1 is false, S3. for said central manager (ξ), constructing a list of available servers on the basis of the availability of each one of said number of local managers given in step S2; S4. if said list of available servers contain at least an element, chooses, among the elements of said list, the server to which said new virtual machine is to be assigned, and assigns the latter to the former; S5. if said list of available servers does not contain any element, activates a server in said subset of inactive servers (v) and assigns to it said virtual machine to be assigned,