Defining sqlhosts information for connection management of high-availability clusters

You must define sqlhosts network-connectivity information for connection management of high-availability clusters.

About this task

To use a file other than $INFORMIXDIR/etc/sqlhosts on a specific host, set the host's INFORMIXSQLHOSTS environment variable to the alternative file.

Procedure

  1. On the host of each Connection Manager and database server, create sqlhosts file entries for each database server in the cluster.
    For example:
    #dbservername   nettype    hostname   servicename   options
 server_1       onsoctcp   host_1     port_1
 server_2       onsoctcp   host_2     port_2
 server_3       onsoctcp   host_3     port_3
  2. On the host of each Connection Manager, add a group entry that contains each database server in the cluster, and add group options to the database-server entries. Use the c=1 group-entry option, so that connection-attempt starting points in the list of group members is random. Use the e=last_member group-entry option so that the entire sqlhosts is not scanned for group members.
    For example:
    #dbservername   nettype    hostname   servicename   options
 my_servers     -          -                        c=1,e=server_3
 server_1       onsoctcp   host_1     port_1        g=my_servers
 server_2       onsoctcp   host_2     port_2        g=my_servers
 server_3       onsoctcp   host_3     port_3        g=my_servers
  3. On the host of each client application, create an sqlhosts file entry for each service-level agreement (SLA) in each Connection Manager configuration file.
    The first Connection Manager's configuration file has the following entries:
    NAME connection_manager_1

CLUSTER my_cluster
{
   INFORMIXSERVER my_servers
   SLA sla_primary_1     DBSERVERS=PRI
   SLA sla_secondaries_1 DBSERVERS=SDS,HDR
   FOC ORDER=ENABLED \
       PRIORITY=1
}
    The second Connection Manager's configuration file has the following entries:
    NAME connection_manager_2

CLUSTER my_cluster
{
   INFORMIXSERVER my_servers
   SLA sla_primary_2     DBSERVERS=PRI
   SLA sla_secondaries_2 DBSERVERS=SDS,HDR
   FOC ORDER=ENABLED \
       PRIORITY=2
}
    Add the following entries to each client application's host sqlhosts file:
    #dbservername       nettype    hostname   servicename   options
 sla_primary_1      onsoctcp   cm_host_1  cm_port_1
 sla_primary_2      onsoctcp   cm_host_2  cm_port_2

 sla_secondaries_2  onsoctcp   cm_host_1  cm_port_3
 sla_secondaries_2  onsoctcp   cm_host_2  cm_port_4
  4. On the host of each client application, create sqlhosts file entries for each group of SLA entries, and add group options to the SLA entries. Use the c=1 group-entry option, so that connection-attempt starting points in the list of group members is random. Use the e=last_member group-entry option so that the entire sqlhosts is not scanned for group members.
    #dbservername       nettype    hostname   servicename  options
 g_primary          group      -          -            c=1,e=sla_primary_2
 sla_primary_1      onsoctcp   cm_host_1  cm_port_1    g=g_primary
 sla_primary_2      onsoctcp   cm_host_2  cm_port_2    g=g_primary

 g_secondaries      group      -          -            c=1,e=sla_secondaries_2
 sla_secondaries_2  onsoctcp   cm_host_1  cm_port_3    g=g_secondaries
 sla_secondaries_2  onsoctcp   cm_host_2  cm_port_4    g=g_secondaries

Results

Client connection requests to @g_primary are directed to one of the Connection Managers. If connection_manager_1 receives the request, it uses sla_primary_1 to provide the client application with connection information for the primary server. If connection_manager_2 receives the request, it uses sla_primary_2 to provide the client application with connection information for the primary server.