高可用内存备份空间创建机制

发布时间：2018-02-13 22:42

本文关键词： 高可用虚拟化镜像内存　出处：《上海交通大学》2013年硕士论文　论文类型：学位论文

【摘要】：云计算集群的规模正日益增大，对可用性要求也越来越高。文献显示对于商业云计算公司而言，每分钟的宕机可能造成数万美元的损失。然而最近的研究表明在大规模云计算环境下，每年约有32%的机器会出现内存错误，更有1.3%的机器会因此导致机器重启或者数据异常。内存错误在大规模集群中，可以被认为是一种常态化的现象，因此提升内存的可用性在今天变得越发重要。传统的内存可用性提升方式可以分为硬件方式和软件方式。硬件方式包括镜像内存与ECC内存，这两类技术都需要特殊的硬件支持。软件方式也可分为两类,一类从应用层对关键数据进行备份，，另一类方式使用虚拟化技术对整机进行备份，这些方式性能相对较为低下。本论文希望以软件方式实现镜像内存系统，它将为内存中的原空间创建出相应的备份空间，供备份数据存储。本论文分别在两套独立的层面实现上述功能：一种是基于操作系统层、轻量、高效的备份空间创建，即Memv6；另一种是基于虚拟化技术、对操作系统透明的Memvisor。在Memv6中，通过修改操作系统的内存管理模块，使得在创建原页表时，同步地创建备份页表，从而完成备份空间的建立。此外，为了保证原空间的地址范围与备份空间的地址范围不产生冲突，本论文分析了操作系统中的内存布局，并对原始布局进行了相应修改，保证了系统的正确性。 Memvisor使用虚拟化技术完成了类似功能。通过修改直接页表技术中的页表创建流程，或者修改影子页表技术中的页表翻译流程，完成备份空间的创建。虚拟化技术可以屏蔽操作系统对备份空间创建的可见性，增大了应用范围。此外，它也允许在一个物理机上同时运行高可用虚拟机和非高可用虚拟机，相比硬件高可用方案更为灵活。实验显示，所有的原空间都成功创建了相应的备份空间，一个200KB的备份空间创建所需的额外时间少于1毫秒，对于xv6命令的性能影响为5%-8%，对小型Web服务器thttpd性能影响小于5%。相较于其他软件高可用技术，其造成的性能影响仅为它们的5%~10%。
[Abstract]:Cloud computing clusters are growing in size and demand for availability. The literature shows that for commercial cloud computing companies, Downtime per minute can cost tens of thousands of dollars. But recent research shows that about 32% machines in large-scale cloud computing suffer from memory errors each year. More than 1.3% machines can cause machine restarts or data anomalies. Memory errors can be considered a regular phenomenon in large clusters, so improving memory availability is becoming more and more important today. The traditional methods of improving memory availability can be divided into hardware mode and software mode. Hardware mode includes mirrored memory and ECC memory, both of which require special hardware support. One is to backup critical data from the application layer, the other is to use virtualization technology to back up the whole machine. These methods have relatively low performance. This paper hopes to realize the mirror memory system by software, which will create the corresponding backup space for the original space in the memory. This paper implements the above functions in two independent layers: one is based on the operating system layer, light, efficient backup space creation, that is Memv6; the other is based on virtualization technology, transparent to the operating system Memvisor. In Memv6, the backup page table is created synchronously when the original page table is created by modifying the memory management module of the operating system. In order to ensure that there is no conflict between the address range of the original space and the address range of the backup space, this paper analyzes the memory layout in the operating system, and modifies the original layout to ensure the correctness of the system. Memvisor uses virtualization to do this by modifying the page table creation process in the direct page table technology, or by modifying the page table translation process in the shadow page table technology. Virtualization technology can mask the visibility of the operating system to create backup space and increase the scope of application. In addition, it also allows to run both highly available and non-highly available virtual machines on a physical machine. It is more flexible than the hardware high availability scheme. The experiment shows that all the original spaces have been successfully created, and the extra time required to create a 200KB backup space is less than 1 millisecond. The performance effect of the xv6 command is 5- 8, and the effect on the thttpd performance of the small Web server is less than 50.Compared with other highly available software technologies, the performance impact is only 510% of them.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP333;TP309.3

【共引文献】