How could we configure an SQL Server Always On Availability Group with a multi-subnet network?
Right click on the SQL Server service and select properties. Select the “AlwaysOn High Availability” tab, and check the box to enable it. You will see the Windows cluster name which will be automatically fetched by this service in the “Windows failover cluster name” section.
What is multi-subnet network?
A SQL Server multi-subnet failover cluster is a configuration where each failover cluster node is connected to a different subnet or different set of subnets. These subnets can be in the same location or in geographically dispersed sites.
How to create multiple subnet AlwaysOn availability group?
1.Register your subscription on for all servers (red1,red2,red3 and red4 in this case) 2.List all available subscription, pick the one with High Availabiilty , notedown the pool id 3.Register the subscription for all nodes (red1,red2,red3 and red4 in this case) 5.Install Pacemaker packages on all nodes. (red1,red2,red3 and red4 in this case)
How to deploy SQL Server always on availability groups?
Deploying SQL Server AlwaysOn Availability Groups requires a Windows Server Failover Clustering (WSFC) cluster and each availability replica of a given availability group must reside on a different node of the same WSFC cluster. I am assuming the readers of this post have basic knowledge about AlwaysOn and its components.
Why do we need a multi subnet failover cluster?
With data replication, there is more than one copy of the data available. Therefore, a multi-subnet failover cluster provides a disaster recovery solution in addition to high availability. The following illustration represents a two node, two subnet failover cluster instance (FCI) in SQL Server.
Is there way to support multiple subnets in Windows?
In the Windows world, a Windows Server Failover Cluster (WSFC) natively supports multiple subnets and handles multiple IP addresses via an OR dependency on the IP address. On Linux, there is no OR dependency, but there is a way to achieve a proper multi-subnet natively with Pacemaker, as shown by the following.