**9. Conclusion**

This chapter covered the importance of business continuity in a cloud environment and how business continuity enables to achieve the required service availability. First, we briefly introduced cloud computing, including background, properties, advantages and challenges. This chapter also covered various fault tolerance mechanisms for cloud infrastructure to eliminate single points of failure. This chapter further covered data protection solutions such as backup and replication. Then, we discussed the details of DRaaS approaches. In addition, we also derived the main challenges of DRaaS mechanisms and proposed solutions to overcome them. Furthermore, the main DRaaS platforms are discussed, followed by open issues and future directions in the field of DRaaS mechanisms. Finally, this chapter also covered the key design strategies for cloud application resiliency.

Finally and as a proof of concept of cloud DR solutions, Microsoft Azure is used. Microsoft Azure is the public cloud to offer Disaster Recovery solution for applications running on Infrastructure as a Service (IaaS) by replicating VMs into another region even failure occurs on region level. The second proposed solution is a way of implementing highly available virtualized network element using Microsoft Windows Server and Microsoft System Center tools called High Availability Solution over Hybrid Cloud Using Failover Clustering Feature. The two solutions were successfully implemented and provided high performance and excellent results.

### **Author details**

Wagdy Anis Aziz1 , Eduard Babulak<sup>2</sup> \* and David Al-Dabass<sup>3</sup>


\*Address all correspondence to: babulak@yahoo.com

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Network Function Virtualization over Cloud-Cloud Computing as Business Continuity Solution DOI: http://dx.doi.org/10.5772/intechopen.97369*
