Virtualization technologies enable the execution of multiple virtual machine instances (VMs) with different operating systems (OSs) on the same physical host. Each VM instance functions independently as an isolated system with its own physical resources, OS and applications. Due to significant cost saving and efficiency, the virtualization model has been increasingly adapted by enterprises and service providers as their main computing and service delivery infrastructure, running critical internal business and external customer facing applications. To minimize down time due to unexpected VM crashes, a high availability or backup system is usually built into the infrastructure. There are many high availability technology options available such as replication, mirroring and fail over clustering. Most of these solutions are usually designed based on the traditional computing model, they are costly to implement, complicated and tedious to maintain, especially in a virtualized environment, and they often require additional expensive hardware and software components. In this paper, we introduce a simple, flexible, scalable, extensible, efficient and cost effective system which utilizes the current VM infrastructure and common utilities to provide a high availability solution in the virtualization environment. Our smart adaptive snapshot replication technique provides a smooth and reliable mechanism for cost-performance, wherein the amount of resources allocated for high availability solution can be adjusted based on available resources, utilization and customer requirements. © 2012 ACM.