You can't connect to a SQL Server instance configured with more than 64 IP addresses.īoth SQL Server Authentication or Kerberos Authentication can be used with MultiSubnetFailover=Yes, without affecting the behavior of the application. Specify the availability group listener of the availability group as the server in your connection string.
Specify MultiSubnetFailover=Yes to improve performance when you're connecting to a single subnet or multi-subnet availability group. When you're connecting to a server in an availability group or failover cluster instance: Otherwise, your application's performance can be negatively affected.
Use MultiSubnetFailover=Yes when you're connecting to an availability group listener or failover cluster instance. MultiSubnetFailover=Yes applies to both single- and multi-subnet availability groups and failover cluster instances. MultiSubnetFailover=Yes enables faster reconnection after failover of either an Always On availability group, or an Always On failover cluster instance. When you connect with MultiSubnetFailover=Yes, the client retries TCP connection attempts faster than the operating system's default TCP retransmit intervals. The driver tries to connect to the database on the primary SQL Server instance by trying to connect to all the IP addresses. The MultiSubnetFailover connection property indicates that the application is being deployed in an availability group or failover cluster instance. During a subnet failover, the driver aggressively retries the TCP connection. During a multi-subnet failover, the client attempts connections in parallel. This connection property also significantly reduces failover time for single and multi-subnet Always On topologies. MultiSubnetFailover enables faster failover for all availability groups and failover cluster instances in SQL Server 2012 (11.x). Connect with MultiSubnetFailoverĪlways specify MultiSubnetFailover=Yes when you're connecting to a SQL Server 2012 (11.x) availability group listener or SQL Server 2012 (11.x) failover cluster instance. Increasing the connection timeout and implementing connection retry logic increases the chance of connecting to an availability group. Retry a failed connection until it reconnects. If a connection attempt succeeds, the driver discards any pending connection attempts.īecause a connection can fail due to an availability group failover, you should implement connection retry logic. When you're connecting to an availability group listener, the driver attempts to establish connections to all IP addresses in parallel. If the DNS server's first returned IP address isn't connectable, these iterations can be time consuming.
MICROSOFT® ODBC DRIVER 11 FOR SQL SERVER MACOS DRIVERS
The ODBC drivers on Linux and macOS iterate sequentially through all IP addresses associated with a DNS hostname, if you aren't connecting to an availability group listener. The application must open a new connection to continue work after the failover. If an ODBC application on Linux or macOS is connected to a database in an availability group that fails over, the original connection is broken. You can specify the availability group listener of a particular availability group in the connection string. For more information about Always On availability groups, see:Īvailability group listeners, client connectivity, and application failover (SQL Server)Ĭreation and configuration of availability groups (SQL Server)įailover clustering and Always On availability groups (SQL Server)Īctive secondaries: Readable secondary replicas (Always On availability groups) The ODBC drivers for Linux and macOS support Always On availability groups.
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