For installing RACONE we need to install:
1. Grid infrastructure
2. RAC software in all the nodes
3. While creating a DB using DBCA select RAC One node option. DBCA can be used only above 11.2.0.2. In version 11.2.0.1 we will have to use command line utility provided by oracle.
Some of the issues found:
1. This feature works best in 11.2.0.2 and above. In version 11.2.0.1
dataguard is not supported. Administration of RACONE in 11.2.0.1 will be using command line tool. These tools are not user friendly. There is mandatory patch(#9004119) which needs to be applied to 11.2.0.1
2. OEM 11.1 doesnât support RACONE. It doesnât understand the failover or relocate option.
3. OEM 11.1 doesn't recognize the racone db automatically. We will have to manually add the entries to OEM 11.1. Any failover or relocate we will have to do it manually.
4. Configuration type in DBCA should be Admin-Managed and not
Policy-Managed
5. When the inst_1 is running via racone, you can actually open the inst_2 in node 2. Technically we can have both the instance running. Though Inst_2 will use different service name than that of inst_1. This will confuse the DBA whether the itâs racone or not. But one good thing is all the racone instance will end with underscore and a number.
Crashing instance/node (failover):
When the node goes down or kill the pmon (kill -9 pmon), then
cluster first tries to restart the instance in same node. If it is
unsuccessful, it will start the instance in other node. In the other node it will start with same name. Say If the instance name is inst_1, when it failover to node 2 it will be still inst_1.
If you shutdown the db using shutdown abort/immediate, then
cluster DOESNâT start the db automatically. The user sessions which are connected during failover will be disconnected. Users needs to open a new session.
Relocate(switchover):
If you are relocating instance inst_1 from node 1 to node 2, it
will create init.ora automatically in node 2. In node 2 it will start with
different instance name, say inst_2.
The user sessions which are connected during switchover will
remain connected. But any query which is running during the relocate phase will fail. User has to reissue the query.
Post switchover, it uses different instance name. In failover it retains the same instance name.
Convert:
You can convert the db from RACONE to RAC or vice versa using
simple commands.
Some important commands,
srvctl relocate database -d inst_1 -n node2 inst_1 relocated to node 2.
srvctl config database âd <db_unique_name> ï Using this command you can figure out whether the db is RACONE or not.
srvctl convert database âd <db_unique_name> -c RAC/RACONE ï Convert the db to RAC or RACONE