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.

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

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

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
```

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

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

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

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

Results

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.