Managing Server Pools with Earlier Database Versions

Starting with Oracle Grid Infrastructure 12c, Oracle Database server categories include roles such as Hub and Leaf that were not present in earlier releases.

For this reason, you cannot create server pools using the Oracle RAC 11g Release 2 (11.2) version of Database Configuration Assistant (DBCA). To create server pools for earlier release Oracle RAC installations, use the following procedure.

Log in as the Oracle Grid Infrastructure installation owner (Grid user).
Change directory to the 12.2 Oracle Grid Infrastructure binaries directory in the Grid home. For example:
```
# cd /u01/app/12.2.0/grid/bin
```
Use the Oracle Grid Infrastructure 12c version of srvctl to create a server pool consisting of Hub Node roles. For example, to create a server pool called p_hub with a maximum size of one cluster node, enter the following command:
```
srvctl add serverpool -serverpool p_hub -min 0 -max 1 -category hub;
```
Log in as the Oracle RAC installation owner, start DBCA from the Oracle RAC Oracle home. For example:
```
$ cd /u01/app/oracle/product/12.2.0/dbhome_1/bin
$ dbca
```
DBCA discovers the server pool that you created with the Oracle Grid Infrastructure 12c srvctl command. Configure the server pool as required for your services.