JR57960: MULTISUBNETFAILOVER SUPPORT WHEN CONNECTING TO MS SQL SERVER USING ODBC CONNECTOR

APAR status

• Closed as Vendor Solution.

Error description

• The MultiSubnetFailover connection parameter support to the SQL
  Server ODBC Driver by DataDirect.
  
  The driver (VMsqls00.so) build supporting this functionality is
  07.16.0350 (B0357, U0237) or later on Linux 64-bit. On other
  platforms this has been fixed in the driver version: 07.16.0355
  (B0362, U0241) or later.
  
  To utilize the new functionality, you will need to set the new
  connection property "MultiSubnetFailover" to 1 in your data
  source. With MultiSubnetFailover enabled, you should set the
  driver's HostName property to the DNS name of the SQL Server
  Always On Availability Group Listener. In an Always On
  environment, the listener name maps to all the IP address of
  the Availability Group listeners in the cluster. When
  connection failover occurs, the driver will ask DNS for the
  list of IP addresses associated with the listener name and
  attempt to reconnect to all of the IPs in parallel. Whichever
  connection succeeds first will be kept and the other connection
  attempts discarded.
  
  Since the driver dynamically determines the IP addresses of the
  listeners through DNS look up, using the MultiSubnetFailover
  option will cause the driver to ignore the existing
  AlternateServers connection property that was previously used
  to define the server list to which the driver should attempt to
  connect when failover occurs.
  
  Note that this driver also supports the Application Intent
  feature of an Always on cluster. Application Intent is a
  request for the driver to ask the SQL Server listener for
  connectivity to either a read only or read/write node within
  the cluster. We have found that the setting is not treated as a
  requirement by the listener. For example, if I set
  ApplicationIntent to ReadOnly and the cluster only has
  Read/Write nodes defined, then the connection to one of those
  nodes will succeed. The driver has no control over this as it
  is the responsibility of the listener to route the connection
  to one of the nodes in the Availability Group. If a ReadOnly
  node is available in this scenario, then the connection is
  properly routed to that node.
  

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

• The driver build containing this feature support is
  LINUX64-71-odbc71-170605.tar.gz
  
  This feature has been implemented from the DataDirect SQL Server
  ODBC Driver version starting from: 07.16.0350 (B0357, U0237).
  
  In addition to using this driver, the following connection
  parameters need to be set in the corresponding ODBC DSN stanza
  in the odbc.ini file:
  
  MultiSubnetFailover=1
  HostName=DNS name of the SQL Server Always On Availability Group
  Listener
  

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

Applicable component levels