Lightweight Checkpoint Of Virtual Machine Memory

With the development of the cloud computing, the size of the cloud computing continues to expand. More and more services are provided on the cloud platform. Cloud computing has become a new opportunity, while inevitably brings challenges and problems. Security issues has become critical on the cloud platform, the failure of cloud platform can bring disastrous consequences. Virtual machine as the most basic resources in the cloud platform, taking checkpoint of it is important. This technology is widely used in fault tolerant and disaster recovery system.The traditional VM checkpoint’s size is very large and downtime is long. In order to solve the problem of VM checkpoint, copy-on-write, incremental mechanism, and page eviction were proposed. Memory compression and free page eviction can avoid saving useless page in checkpoint file. In this way, the size of checkpoint file can be greatly reduced. With copy-on-write mechanism, the checkpoint downtime should be as short as possible so as to keep the VM transparent to the service. Incremental checkpoint is an effective optimization approach to reduce the checkpoint overheads by only saving dirty pages from last checkpoint when there is need to make frequent checkpoints. These three technologies can make the checkpoint technology.The experiment shows that with copy-on-write checkpoint mechanism, it can reduce the checkpoint shutdown time. While taking checkpoint, the downtime was no more than300ms. With free page eviction and incremental mechanism, the size of checkpoint file was reduced to80%. In this way, we can save a lot of resources which system do the high frequency of checkpoint system.