Renovating legacy distributed systems using virtual appliance with dependency graph

Legacy distributed systems hosted on old infrastructures can be renovated using virtual appliance that is a package of virtual machines, installed applications and their configurations. By converting a legacy distributed system to a virtual appliance, we can conserve the entire system and restart the application on the specific virtualization platforms. However, in order to execute the application service properly on the new hosting environment, some additional network configurations are required to resolve the dependencies inherited in the original system. In this paper, we propose a framework named DS Renovator that converts a legacy distributed system to a virtual appliance and renovates the system on a new hosting environment with optimum deployment for resolving the dependencies. In the virtual appliance generation process, DS Renovator analyzes server dependencies inherent in the legacy distributed system and generates a dependency graph that consists of nodes and edges representing servers and their dependencies respectively. In the virtual appliance deployment process, DS Renovator applies graph partitioning algorithm to the dependency graph to determine the optimum virtual machine placement which minimizes the dependencies between the hosting servers under the capacity limitations. As a graph partitioning algorithm, we propose an edge-contraction based efficient algorithm. The performance of the proposed algorithm is evaluated with case studies in comparison to other approximation algorithms.