Sql-server – How to back up On Premise Microsoft SQL Server 2008 to Azure cloud

I realize this is an old question but may come in handy for others facing similar dilemma.

Your client is correct. Do no open up ports to the world, as this is will create a security risk. You will want a site-to-site VPN between your back offices and "the cloud". Once this is implemented the "the cloud" SQL will be accessible as if it was in your LAN.

For platform-as-a-service (PaaS) databases, you don't get to design the underlying hardware such as CPU, I/O or memory configuration.

You can only choose a service tier that gives you a general idea of the overall performance. On Azure SQL Database, the different service tiers are defined by something Microsoft calls "DTUs", a performance metric that blends disk and CPU performance, but you cannot prioritize one over the other. I suspect AWS RDS works similarly in this regard.

The reason (personal opinion) why you would choose PaaS over IaaS (installing SQL Server on a VM) is that you don't have to maintain and patch any infrastructure. Your colleague is correct in saying that this comes at a price: less freedom.

The upside with PaaS is that you can scale it up and down whenever you need, minute by minute or hour by hour.