Research And Implementation Of Virtual Machine Hot Standby System Based On KVM

In recent years, as virtualization technology becomes more and more mature, cloud computing is also growing rapidly. In the current cloud computing environment, virtualization technology is mainly used to implement the service resource scheduling and sharing, and all services are applied based on virtual machine as service background which makes virtual machine's high availability become more important research topics. Due to the high reliability and short downtime of the Hot Standby technology, now virtual machine disaster recovery systems are based on it.Virtual machine hot standby system design generally requires short migration time, short downtime and small transmission data each time so that to minimize the impact of hot standby process on the whole system. By analyzing the memory state synchronization process, this paper presents a checkpoint postponed transmission method to reduce virtual machine downtime--PMT-Checkpointing. The method uses a pre-copy algorithm to memory state transition and first caches the status data in QEMU local area during state synchronization and immediately restart the virtual machine, then transfers the status data to the backup virtual machine. The PMT-Checkpointing method divide this process into two halves, that the virtual machine just pause in the first part, and the last part can be performed while the virtual machine is running, which will reduces the downtime, and cache used in the state of the synchronization process is adaptive that adjusts its size with the size of the state of the data, which also reduces the use of memory during state synchronization.PMT-Checkpointing method is implemented in the KVM platform, by testing the method with another hot standby project--Kemari found that in the system idle time Kemari has small impact on network bandwidth, while the system is running I / O-intensive when applications, PMT-Checkpointing method has less impact on network bandwidth, which is the way the two methods to be implemented, the former is the event trigger and the later is checkpoint.