Analysis of an offloading scheme for data centers in the framework of fog computing
Résumé
In the context of fog computing, we consider a simple case when data centers
installed at the edge of the network are backed up by a central (bigger) data
center. The system considered precisely comprises two data centers in parallel.
We assume that if a request arrives at an overloaded data center, it is
forwarded to the other data center with a given probability. Both data centers
are assumed to have a large number of servers (rescaling of the system) and
that traffic to one of them is causing saturation so that the other data center
may help to cope with this saturation regime by reducing the rejection of
requests. Our aim here is to qualitatively estimate the gain achieved by the
collaboration of the two data centers. After proving some convergence results,
related to the scaling limits of loss systems, for the process describing the
number of free servers at both data centers, we show that the performance of
the system can be expressed in terms of the invariant distribution of a random
walk in the quarter plane. By using and developing existing results in the
technical literature, explicit formulas for the blocking rates of such a system
are derived.