Server migration service provides network applications (NW Apps) with server running environment on a computer (WP) and service of server migration to another WP where the NW App can attain better QoS when it is degraded. Because the file size of a server is large, the traffic for server migration causes QoS degradation of its background traffic. Thus, it is important to decrease the degree (impact) of the QoS degradation. In this paper, we propose three destination selection algorithms MIA, MRA and MCA that try to decrease the impact while increasing the number of NW App's clients whose SLA are satisfied. When a server migration is triggered, MIA, MRA and MCA move the server to the WP with the minimum impact, the WP with the maximum remaining space for servers and the WP with the maximum communication range where the SLA is satisfied, respectively. Numerical examples show that when there is no full-cover WP (on which a server can communicate with an arbitrary client while satisfying the SLA) or its space is small, MIA outperforms the others, otherwise MCA outperforms the others.
