Defining sqlhosts information for high-availability clusters that use Distributed Relational Database Architecture (DRDA)

Connection Managers support Distributed Relational Database Architecture™ (DRDA) connections for high-availability clusters. You must define sqlhosts network-connectivity information for connection management of high-availability clusters that use DRDA.

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

  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_3     port_2
     server_3       onsoctcp   host_5     port_3
  2. In each database server's onconfig file, set the DBSERVERALIASES parameter to specify an alias for the server.
    The onconfig file entry for server_1:
    DBSERVERALIASES drda_1
    The onconfig file entry for server_2:
    DBSERVERALIASES drda_2
    The onconfig file entry for server_3:
    DBSERVERALIASES drda_3
  3. On the host of each Connection Manager, add entries for the DRDA aliases. Use a DRDA protocol for the nettype value. 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
    
     drda_1         drsoctcp   host_1     port_4
     drda_2         drsoctcp   host_2     port_5
     drda_3         drsoctcp   host_3     port_6
  4. On the host of each Connection Manager, add a group entry for the group of database server and add a group entry for the group of DRDA aliases. Add group options to the database server and DRDA alias 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     group      -          -             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
    
     drda_aliases   group      -          -             c=1,e=drda_3
     drda_1         drsoctcp   host_1     port_4        g=drda_aliases
     drda_2         drsoctcp   host_2     port_5        g=drda_aliases
     drda_3         drsoctcp   host_3     port_6        g=drda_aliases
  5. 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_primary_drda_1     DBSERVERS=PRI
       SLA sla_secondaries_1      DBSERVERS=SDS,HDR
       SLA sla_secondaries_drda_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_primary_drda_2     DBSERVERS=PRI
       SLA sla_secondaries_2      DBSERVERS=SDS,HDR
       SLA sla_secondaries_drda_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
    
     sla_primary_1_drda      drsoctcp   cm_host_1  cm_port_5
     sla_primary_2_drda      drsoctcp   cm_host_2  cm_port_6
    
     sla_secondaries_2_drda  drsoctcp   cm_host_1  cm_port_7
     sla_secondaries_2_drda  drsoctcp   cm_host_2  cm_port_8
  6. On the host of each client application, create sqlhosts file group 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
    
     g_primary_drda          group      -          -            c=1,e=sla_primary_2_drda
     sla_primary_1_drda      drsoctcp   cm_host_1  cm_port_5    g=g_primary_drda
     sla_primary_2_drda      drsoctcp   cm_host_2  cm_port_6    g=g_primary_drda
    
     g_secondaries_drda      group      -          -            c=1,e=sla_secondaries_2_drda
     sla_secondaries_2_drda  drsoctcp   cm_host_1  cm_port_7    g=g_secondaries_drda
     sla_secondaries_2_drda  drsoctcp   cm_host_2  cm_port_8    g=g_secondaries_drda
Client connection requests to @g_primary_drda are sent by drsoctcp protocol to one of the Connection Managers. If connection_manager_1 receives the request, it uses sla_primary_1_drda to provide the client application with connection information for the primary server. If connection_manager_2 receives the request, it uses sla_primary_2_drda to provide the client application with connection information for the primary server.

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