基于快照的虚拟磁盘镜像检查点系统

基于快照的虚拟磁盘镜像检查点系统 A Comprehensive Checkpoint Mechanism for Virtual Disk Image 何艳丽 HE Yanli 1 first-author 邹德清 ZOU Deqing 1 孔华峰 KONG Huafeng 2 王胜 WANG Sheng 1 华中科技大学计算机科学与技术学院 华中科技大学计算机科学与技术学院 School of Computer Science and Technology,Huazhong University of Science and Technology School of Computer Science and Technology,Huazhong University of Science and Technology 公安部第三研究所 公安部第三研究所 The Third Research Institute of Ministry of Public Security The Third Research Institute of Ministry of Public Security 在当前Xen内置检查点机制中,并未涉及磁盘状态的备份.为保证虚拟机持久状态与瞬时状态的一致性,虚拟机的磁盘状态信息也应该做备份.本文提出的虚拟镜像检查点系统提供了一种可与Xen内置检查点结合的方案来共同保存完整虚拟机状态.虚拟磁盘镜像检查点采用磁盘快照的方式实现,通过更新引用计数和保存磁盘的一级表的形式建立磁盘检查点,在恢复检查点时,只需再次更新磁盘块的引用计数,将之前保存的一级表写入到当前一级表即可.功能测试和性能测试表明,该系统能正确恢复虚拟机出错前的磁盘状态,降低了磁盘检查点设置时间开销和建立快照之后的写操作带来的空间开销. The current checkpoint mechanism of Xen does not address the state of external storage.To ensure the persistent state of VM（virtual machine）to be consistent with its transient state,the disk state of the running VM should also be snapshotted.To save the full state of the VM,we propose a combination of memory checkpoint with disk snapshot.Disk checkpoint is implemented by updating the reference count of disk blocks and saving the current L1 table to the disk.To restore the checkpoint,we just need to update the reference count and write the old L1 table to the current one.The functional test and performance test indicate that our system can correctly restore the disk state of the fault VM,meanwhile the disk checkpoint set time and the checkpoint storage overhead are decreased. 虚拟化 容错 虚拟机 磁盘检查点 一致性 virtualization fault-tolerant virtual machine disk checkpoint consistence 10.14188/j.1671-8836.2014.06.006 TP309.3 国家高技术研究发展（863）计划（2012AA012600）资助项目 2014-06-01 2021-04-01 6 60