On demand clock synchronization for live VM migration in distributed cloud data centers

Live migration of virtual machines (VMs) has become an extremely powerful tool for cloud data center management and provides significant benefits of seamless VM mobility among physical hosts within a data center or across multiple data centers without interrupting the running service. However, with all the enhanced techniques that ensure a smooth and flexible migration, the down-time of any VM during a live migration could still be in a range of few milliseconds to seconds. But many time-sensitive applications and services cannot afford this extended down-time, and their clocks must be perfectly synchronized to ensure no loss of events or information. In such a virtualized environment, clock synchronization with minute precision and error boundedness are one of the most complex and tedious tasks for system performance. In this paper, we propose enhanced DTP and wireless PTP based clock synchronization algorithms to achieve high precision at intra and inter-cloud data center networks. We thoroughly analyze the performance of the proposed algorithms using different clock measurements. Through simulation and real-time experiments, we also show the effect of various performance parameters on the data center networking architectures. (C) 2019 Elsevier Inc. All rights reserved.