Optimizing live migration of virtual machines across wide area networks using integrated replication and scheduling

Migrating virtual machines (VM) at run time within acceptable time limits is significantly challenging due to large size of the virtual disk files. In this paper, we propose our framework called cloudspider to overcome this challenge by combining replication and scheduling of VM images into a common framework. In particular, we replicate VM images apriori onto a few chosen cloud sites and select one of the replicas of the VM image to be the primary copy. Based on dynamically changing cost parameters at these cloud sites, the scheduler can appropriately select a different replica of a VM image to be the primary copy. The updates at the primary copy are incrementally propagated to the remaining copies. In order to bring down the cost of storage requirement due to the additional replicas our work proposes the use of deduplication techniques. In this paper we address the question of replica placement of VM images when disparate VM images have varying degrees of commonality and latency requirements. The replication algorithm has been implemented and tested using an open-source cloud simulator called CloudSim and the initial results are quite promising.