In my role as an Azure specialist I get asked a lot of questions about Disaster Recovery. IMHO they almost always ask the wrong question.
Usually it goes something like “I need Disaster Recovery protection for my data center. I have N VMs to protect. I have heard that I can use Azure Site Recovery either to facilitate Disaster Recovery to my backup data center, or even use Azure as my backup data center.” That is true.
In a previous lifetime I used to work on a Disaster Recovery testing team for a major New York based international bank. We learned early on two major principles:
1. It is all about workloads since different application workloads have different Disaster Recovery requirements. Every workload has unique Recovery Time Objectives (RTO) and Recovery Point Objectives (RPO). Not all workloads are created equal. For instance email is a critical workload in the typical enterprise. An outage of more than a few hours would affect business continuity significantly. Other application workloads (such Foreign Exchange Trading, Order Processing, Expense Reporting, etc.) would have more or less stringent RTO and RPO requirements.
2. So it is really is all about Business Continuity. Disaster Recovery is a business case. It is clear that providing perfect Disaster Recovery for all application workloads would be extremely expensive; and in many cases not cost effective. In effect there is an exponential cost curve. So it is all about risk management and cost/benefit.
So where does that leave us?
1. Evaluate your Disaster recovery requirements on a workload by workload basis.
2. Plan how to implement it considering the objective of Business Continuity, RTO and RPO.
3. Use Azure Site Recovery to make it happen.