IRB guidelines for secure online data storage, backup, and syncing?
While this solution will likely be only a drop in the bucket for your request, I did write a paper covering security issues related to health information and HIPAA while finishing up my Master's. Section 6 has a case study on Amazon Web Services as a "HIPAA-compliant" cloud storage solution, including both its positives and its negatives.

Since this was a review paper, I feel the need to point out that I don't have any personal experience with Amazon Web Services or with setting it up for HIPAA compliance, so don't take it as an endorsement either for or against its use.

It's important to evaluate exactly what any proposed service you select actually provides. AWS, for example, supports basically the creation of the HIPAA-compliant environment. That being said, that's the creation of one, not one provided out of box. You'd have to implement a variety of features normally associated with data storage such as backing up data, auditing all changes, and so on.

Basically, you're asking what you need to do to satisfy the IRB, I guess. What you should probably be asking is what you can do to satisfy HIPAA regulations, and using that, justify that it is a viable solution to the IRB.

I can't really provide you a concrete example of an actual cloud data storage plan (the one I was involved in is non-disclosure and I'm also not an IS guy) but I might be able to answer some more conceptual questions.