This book presents an approach for providing high availability to the requests of cloud¿s clients. To achieve this objective, fail-over strategies for cloud computing data centers using integrated multilevel checkpointing algorithms are proposed in this research work. Proposed strategy integrates checkpointing features with load balancing algorithms and also employs multilevel checkpointing to decrease checkpointing overheads. Additional objective of this research work is to improve the checkpointing efficiency and prevent checkpointing from becoming the bottleneck of cloud data centers. In this book, greencloud simulator is used for energy-aware cloud computing data centers. Along with the workload distribution, the simulator is used to capture details of the energy consumed by data center components (servers, switches, and links) as well as packet-level communication patterns in realistic setups.