I have a question about using multiple subnets in a AlwaysOn Availability group. We have a AlwaysOn setup (SQL 2012) already in production that has a listener that is configured for 2 subnets. 1 of these is local and the other is used for DR. Obviously, we want to avoid anything being routed through the DR subnet on everyday use. We had an issue where when we first did this that we experienced timeouts. The ways to overcome this is well-documented and we have implemented fixes and looking at some of the alternate ways.
Primarily, we are using “MultiSubnetFailover=True” in our connection strings, but we are looking at modifying the RegisterAllProviderIP cluster resource setting to 0 due to some limitations on the MultiSubnetFailover parameter to handle this and then just working around the slower cutover time as a result. The only other subnet we are using is DR so I think this is manageable.
My question though is if AlwaysOn changed the way connections are made in any of the newer versions of SQL (or .NET Framework) that prevents the need to do some of this. We are currently planning to upgrade the coming year to SQL 2016 and at the same time move to AlwaysOn AG. Is “MultiSubnetFailover=True” or changing the RegisterAllProviderIP still required in SQL 2016 or is any of this handled automatically\different?
Most of the information regarding this is specific to SQL 2012 and I cannot seem to find information that definitively says if this applies for all versions. I did find some articles that mentioned this “MultiSubnetFailover=True” is handled automatically, but not sure if that was just application specific or product specific. Thanks.