Businesses who need high availability and disaster recovery usually want three servers:
- A primary SQL Server where all the writes & reads take place
- A high availability SQL Server sitting right next to the primary, in the same data center, keeping up with its writes, and
- A disaster recovery SQL Server sitting in another city or region, keeping up with the writes, but not necessarily in real time – the writes here are usually asynchronous
There are several different techniques we can use to keep those in sync, like failover clustering, Always On Availability Groups, SAN replication, log shipping, and database mirroring.
Regardless of which technology you use, there’s an important question: do you have to license the standby SQL Servers, aka #2 and #3? Since November 2019, you don’t have to pay licensing for those SQL Servers in most circumstances. Microsoft changed the licensing terms when SQL Server 2019 came out.
As long as your licensing is covered under Software Assurance, you get several new benefits including:
- One high availability server is free
- One disaster recovery server is free
- You can offload corruption checks, full backups, and log backups to these servers too
- But you still can’t query them. As soon as you start offloading end user queries onto them, they need to be fully licensed.
Isn’t that awesome? And the best thing is that you don’t even have to be running SQL Server 2019 in order to get those benefits! As long as you’re current on Software Assurance, you get this on any supported version.
This is the kind of thing that really makes an impact on your high availability and disaster recovery architectures, and I’ll be talking about that on Thursday, June 17th.