广域网中虚拟机实时迁移加速系统的研究和设计

发布时间：2019-05-11 13:44

【摘要】：虚拟机技术因其具有提高物理资源利用率、易于管理等特性而被广泛应用于数据中心和云计算中。作为虚拟机技术中最为重要的功能之一，虚拟机实时迁移可以在保持虚拟机运行的同时，，将其透明的从一台物理计算机迁移到另外一台物理计算机。在单个数据中心或局域网中，它已经被广泛应用于系统维护、资源动态管理和容错管理等。近年来，广域网虚拟机实时迁移逐渐引起了人们的广泛关注，因为它将满足许多重要应用场景的需要，比如数据中心之间的负载均衡、数据中心的扩张、灾难恢复等。现阶段的虚拟机实时迁移技术通常仅限于局域网。许多成熟的实时迁移方案，如VMware VMotion，Citrix XenMotion等，均基于共享存储（SAN或NFS）实现虚拟机磁盘镜像的共享。因而，实时迁移过程中，从源主机传输到目的主机的主要数据是虚拟机的内存状态。预拷贝是最流行的内存迁移方法。使用该方法的虚拟机实时迁移，其数据传输速率将极大的影响实时迁移的总时间长短和总数据量大小，进而影响实时迁移的性能。而实时迁移的数据传输速率则取决于网络条件和实时迁移的数据传输机制。基于以上分析，本论文首先从通信协议的角度，分析了以VMwareVMotion和Citrix XenMotion为代表的虚拟机实时迁移的数据传输机制，指出现阶段的实时迁移主要使用一到两个数目固定的TCP流传输数据，并且TCP流在应用层上交互很少。接着，搭建网络测试床，测试实时迁移的数据传输性能。实验结果表明，即使在链路带宽充分的情况下，随着时延的上升，实时迁移的数据传输速率也会急剧下降，实时迁移的性能也会随之变差。由于时延随着传输距离的增加而变长，为了保证实时迁移的性能，广域网实时迁移需要克服长时延对其数据传输速率的影响。最后，本文设计并实现了一种实时迁移加速系统LMAS。该系统使用一对透明代理服务器加速虚拟机实时迁移的数据传输，这意味着LMAS跟虚拟机监视器完全独立。LMAS网关隧道分成控制信道和数据信道两部分。其中，数据信道使用并行TCP作为数据传输办法。测试结果表明，LMAS支持在1Gbps和10Gbps两种长距离链路上，对包括VMware VMotion和Citrix XenMotion在内的多种实时迁移加速，而且不需要对虚拟机监视器做任何修改。另外，LMAS提供的数据加密功能，还能够保证实时迁移过程中虚拟机的安全性。
[Abstract]:Virtual machine technology is widely used in data center and cloud computing because of its characteristics of improving the utilization of physical resources and easy to manage. As one of the most important functions of virtual machine technology, real-time migration of virtual machine can migrate virtual machine from one physical computer to another while keeping virtual machine running. In a single data center or local area network (LAN), it has been widely used in system maintenance, resource dynamic management and fault-tolerant management. In recent years, real-time migration of WAN virtual machines has attracted more and more attention, because it will meet the needs of many important application scenarios, such as load balancing between data centers, expansion of data centers, disaster recovery and so on. At present, the real-time migration technology of virtual machine is usually limited to local area network (LAN). Many mature real-time migration schemes, such as VMware VMotion,Citrix XenMotion, realize the sharing of virtual machine disk mirror based on shared storage (SAN or NFS). Therefore, in the process of real-time migration, the main data transferred from the source host to the destination host is the memory state of the virtual machine. Pre-copy is the most popular method of memory migration. The data transmission rate of virtual machine real-time migration using this method will greatly affect the total time of real-time migration and the total amount of data, and then affect the performance of real-time migration. The data transmission rate of real-time migration depends on the network conditions and the data transmission mechanism of real-time migration. Based on the above analysis, this paper first analyzes the data transmission mechanism of virtual machine real-time migration represented by VMwareVMotion and Citrix XenMotion from the point of view of communication protocol. It is pointed out that the current real-time migration mainly uses one or two fixed number of TCP streams to transmit data, and TCP streams interact little on the application layer. Then, the network test bed is built to test the data transmission performance of real-time migration. The experimental results show that, even if the link bandwidth is sufficient, the data transmission rate of real-time migration will decrease sharply with the increase of delay, and the performance of real-time migration will also deteriorate with the increase of delay. Because the delay increases with the increase of transmission distance, in order to ensure the performance of real-time migration, real-time migration of wide area network needs to overcome the influence of long delay on its data transmission rate. Finally, a real-time migration acceleration system LMAS. is designed and implemented in this paper. The system uses a pair of transparent proxy servers to accelerate the data transmission of virtual machine real-time migration, which means that LMAS is completely independent of virtual machine monitor. LMAS gateway tunnel is divided into control channel and data channel. Among them, the data channel uses parallel TCP as the data transmission method. The test results show that LMAS supports the acceleration of real-time migration, including VMware VMotion and Citrix XenMotion, on 1Gbps and 10Gbps long-distance links, and does not need to make any changes to the virtual machine monitor. In addition, the data encryption function provided by LMAS can also ensure the security of virtual machine in the process of real-time migration.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP393.2;TP302

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