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 makes multilevel checkpoints to decrease checkpointing overheads. For implementation of proposed fail-over strategies, a cloud simulation environment is developed, which has the ability to provide high availability to clients in case of failure/recovery of service nodes. Also in this book comparison of proposed work is made with existing methods. Additional objective of this research work is to improve the checkpointing efficiency and prevent checkpointing from becoming the bottleneck of cloud data centers. In order to find an efficient checkpoint interval, checkpointing overheads has been also considered in this paper. Traditional checkpointing methods stores persistently snapshots of the present job state and use them for resuming the execution at a later time.