Example of configuring connection management for prioritizing connections and network monitoring

You can install Connection Managers on the hosts of application servers, and then prioritize the connections between specific application servers and the primary server of a high-availability cluster. This configuration allows the highest priority application server to maintain its connection to the cluster's primary server if a portion of the network fails.

You can configure failover for the following conditions:

  • When the primary server becomes inoperative.
  • When an application server loses network connectivity with the primary server.

If network monitoring and failover priority are enabled and a network failure occurs, an application server that loses connectivity to the primary server but maintains connectivity to a secondary server can, through a shared-host Connection Manager, initiate failover to the secondary server. If, however, failover would cause an application server with more priority to lose connectivity to the primary server, the Connection Managers block failover.

Network monitoring and failover priority are enabled by setting the following parameters and attributes in each Connection Manager's configuration file:
  • The Connection Manager's LOCAL_IP parameter
  • A CLUSTER connection-unit's SLA parameters
  • A CLUSTER connection-unit's FOC parameter
  • The FOC parameter's ORDER attribute
  • The FOC parameter's PRIORITY attribute
  1. Install at least two network interface cards on each host. This method prevents the failure of a network interface card from causing client, Connection Manager, or database server connectivity failure.
  2. Install and configure Connection Managers on each application server's host.
    1. Set the LOCAL_IP parameter in each Connection Manager configuration file to the IP addresses of the host's NIC cards. For example:
      The first Connection Manager's configuration file is named cm_1.cfg and has the following entries:
      NAME connection_manager_1
      LOCAL_IP 192.0.2.0,192.0.2.1
      The second Connection Manager's configuration file is named cm_2.cfg and has the following entries:
      NAME connection_manager_2
      LOCAL_IP 192.0.2.2,192.0.2.3
    2. Create service-level agreements for each Connection Manager. For example:
      cm_1.cfg now has the following entries:
      NAME connection_manager_1
      LOCAL_IP 192.0.2.0,192.0.2.1
      
      CLUSTER my_cluster
      
      {
         INFORMIXSERVER my_servers
         SLA sla_1 DBSERVERS=PRI
         SLA sla_2 DBSERVERS=SDS,HDR,RSS
      }
      cm_2.cfg now has the following entries:
      NAME connection_manager_1
      LOCAL_IP 192.0.2.2,192.0.2.3
      
      CLUSTER my_cluster
      
      {
         INFORMIXSERVER my_servers
         SLA sla_3 DBSERVERS=PRI
         SLA sla_4 DBSERVERS=SDS,HDR,RSS
      }
    3. Specify each application server's priority by setting the FOC parameter's PRIORITY attribute for each shared-host Connection Manager. A PRIORITY value must be a positive integer and unique among all the Connection Managers that are configured to manage a specific cluster. If you specify a PRIORITY value in a connection-unit definition, you must set the ORDER attribute to ENABLED, and specify the failover order in the primary server's HA_FOC_ORDER configuration parameter. For example:
      The primary server has the following onconfig file entry:
      HA_FOC_ORDER SDS,HDR,RSS
      cm_1.cfg now has the following entries:
      NAME connection_manager_1
      LOCAL_IP 192.0.2.0,192.0.2.1
      
      CLUSTER my_cluster
      
      {
         INFORMIXSERVER my_servers
         SLA sla_1 DBSERVERS=PRI
         SLA sla_2 DBSERVERS=SDS,HDR,RSS
         FOC ORDER=ENABLED PRIORITY=1
      }
      cm_2.cfg now has the following entries:
      NAME connection_manager_2
      LOCAL_IP 192.0.2.2,192.0.2.3
      
      CLUSTER my_cluster
      
      {
         INFORMIXSERVER my_servers
         SLA sla_3 DBSERVERS=PRI
         SLA sla_4 DBSERVERS=SDS,HDR,RSS
         FOC ORDER=ENABLED PRIORITY=2
      }
  3. Create sqlhosts files that contain network connectivity information for each Connection Manager and database server host.
  4. Optional: Create a password file if you configure secure ports for database servers.
  5. Run the oncmsm utility on each Connection Manager host, to start each Connection Manager.
    On the host of connection_manager_1:
    oncmsm -c cm_1.cfg
    On the host of connection_manager_2:
    oncmsm -c cm_2.cfg
  6. Check each Connection Manager's log file to verify that the Connection Manager started correctly.
The Connection Managers now initiate failover if a network failure occurs, and failover would not cause a higher-priority application server to lose its connectivity to the cluster's primary server.

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