LACK OF TRUST
Trust in a cloud provider is difficult to quantify. It depends on the specific needs of your enterprise, the cloud provider's overall reputation, and the kinds of service-level agreements you have in place. Your organization's level of trust with a specific cloud provider might transition multiple times throughout your relationship, depending on these and other factors.
When you're considering the idea of housing sensitive data inside a public cloud, you should assume that, at some point, you will lose faith that your provider is keeping your data secure to the degree you have deemed appropriate.
Trust issues are often the most difficult to overcome for IT executives when considering whether or not to move data and apps into the cloud.