Live migration is a key technique for virtual machine (VM) management in data center networks, which enables flexibility in resource optimization, fault tolerance, and load balancing. Despite its usefulness, the live migration still introduces performance degradations during the migration process. Thus, there has been continuous efforts in reducing the migration time in order to minimize the impact. From the network's perspective, the migration time is determined by the amount of data to be migrated and the available bandwidth used for such transfer. In this paper, we examine the problem of how to schedule the migrations and how to allocate network resources for migration when multiple VMs need to be migrated at the same time. We consider the problem in the Software-defined Network (SDN) context since it provides flexible control on routing. More specifically, we propose a method that computes the optimal migration sequence and network bandwidth used for each migration. We formulate this problem as a mixed integer programming, which is NP-hard. To make it computationally feasible for large scale data centers, we propose an approximation scheme via linear approximation plus fully polynomial time approximation, and obtain its theoretical performance bound and computational complexity. Through extensive simulations, we demonstrate that our fully polynomial time approximation (FPTA) algorithm has a good performance compared with the optimal solution of the primary programming problem and two state-of-the-art algorithms. That is, our proposed FPTA algorithm approaches to the optimal solution of the primary programming problem with less than 10 percent variation and much less computation time. Meanwhile, it reduces the total migration time and service downtime by up to 40 and 20 percent compared with the state-of-the-art algorithms, respectively.

中文翻译：

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软件定义网络中的虚拟机迁移规划

实时迁移是数据中心网络中虚拟机（VM）管理的一项关键技术，可在资源优化，容错和负载平衡方面实现灵活性。尽管有用，但实时迁移在迁移过程中仍然会导致性能下降。因此，为了减少影响，一直在努力减少迁移时间。从网络的角度来看，迁移时间取决于要迁移的数据量和用于此类传输的可用带宽。在本文中，我们研究了当需要同时迁移多个VM时如何计划迁移以及如何为迁移分配网络资源的问题。我们在软件定义网络（SDN）上下文中考虑该问题，因为它可以灵活地控制路由。更具体地说，我们提出了一种计算最佳迁移顺序和每次迁移所用网络带宽的方法。我们将此问题表述为NP难的混合整数编程。为了使其在大规模数据中心的计算上可行，我们提出了一种通过线性逼近加完全多项式时间逼近的逼近方案，并获得了其理论性能界限和计算复杂性。通过广泛的仿真，我们证明了与主要编程问题的最佳解决方案和两种最新算法相比，我们的完全多项式时间逼近（FPTA）算法具有良好的性能。那是，我们提出的FPTA算法以小于10％的变化和更少的计算时间来解决主要编程问题的最佳解决方案。同时，与最新算法相比，它最多可将总迁移时间和服务停机时间分别减少40％和20％。