Considerations for Exchange Disaster Recovery Architecture

Recently I was involved in planning sessions for a client's Microsoft Exchange 2013 environment. They currently are based in one data center and have been looking to implement highly available and disaster recovery solutions. Of course price seemed to always trump everything, but it may be useful for others out there looking to plan for Exchange HA/DR to make sure your discovery sessions include the below items.

1. What is the recovery time objective? 
• A long RTO could mean that rebuild / restoring from tape is viable
2. What is the recovery point objective?
• How much can be lost - if you need things current, or within minutes last night's tape backup won't work
3. Do you have to have off-site?
• Maybe you only have one data center - could you co-locate? Could an online solution solution such as Acronis or Datto have be viable?
4. Do all mailbox databases need to be readily available?
•  Do you have VIP users with more sensitive RTO/RPO numbers? This could be a way to cut costs if only some of the data is replicated.
5. Do line of business applications require e-mail integration?
• Maybe that document management system running your client data ties into Exchange and your entire business is down if e-mail is down. 
6. Leverage native capabilities! 
• DAGs can extend across multiple sites and provide great resilience against a variety of disasters including point failures such as disk, server, and network or even entire data center failure. (DC failure - that really big point failure!)

These are just a few "big ticket" areas of consideration when planning for HA/DR in an Exchange environment. Starting with these can let you dig into details and begin to prepare options for a client to have a successful e-mail availability and recovery solution.