Improving Availability in Large, Distributed Component-Based Systems via Redeployment

In distributed and mobile environments, the connections among the hosts on which a software system is running are often unstable. As a result of connectivity losses, the overall availability of the system decreases. The distribution of software components onto hardware nodes (i.e., the system's deployment architecture) may be ill-suited for the given target hardware environment and may need to be altered to improve the software system's availability. The critical difficulty in achieving this task lies in the fact that determining a software system's deployment that will maximize its availability is an exponentially complex problem. In this paper, we present a fast approximative solution for this problem, and assess its performance. In addition to significantly improving availability, our solution, in general, also reduces the overall interaction latency in the system. We evaluate our solution on a large number of automatically generated application scenarios (24 References).