Graceful Switchover and RAC
Graceful Switchover can be used with Oracle RAC and works identical to graceful switchover with single instance databases. However the following applies:
1. Graceful Switchover can only occur between ONE primary node and the standby server. The instance on the other primary node(s) will be automatically shutdown during graceful switchover.
For example: With the following configurations:
Primary | Standby |
|---|---|
ServerA – RAC instance | ServerC – Single instance standby database |
ServerB – RAC instance |
|
Graceful Switchover with RAC example
With the following configuration:
Primary | Standby |
|---|---|
ServerA – RAC instance dbvrac1 | ServerC – Single instance standby database dbvrac |
ServerB – RAC instance dbvrac2 |
|
Graceful Switchover is initiated on both ServerA and ServerC with command:
The following will occur:
1. RAC database dbvrac2 on ServerB will be shutdown.
2. RAC database dbvrac1 will be converted to a single instance standby database.
3. Single instance standby database on ServerC will be converted to a single instance primary database with 2 threads:
Standby | Primary |
|---|---|
ServerA – Single instance standby database dbvrac1 | ServerC – Single instance primary database dbvrac |
ServerB – RAC instance shutdown |
If Graceful Switchover is initiated again to bring it back to the original configuration the following will occur:
1. Single instance standby database dbvrac1 on ServerA will be converted to a single instance primary database with 2 threads.
2. Single instance primary database dbvracon ServerC will be converted to a single instance standby database with 2 threads:
Primary | Standby |
|---|---|
ServerA – Single instance primary database dbvrac1 | ServerC – Single instance standby database dbvrac |
ServerB – RAC instance shutdown |
|
To convert from a single instance primary database back to a RAC database:
1. On ServerA, set database parameter cluster_database=TRUE in database dbvrac1.
2. Restart instance dbvrac1 on ServerA.
3. Start dbvrac2 instance on ServerB.
4. Dbvisit Standby can be initiated again as normal on ServerA and ServerC:
5. On other nodes that were not part of the graceful switchover (in this case ServerB), Dbvisit Standby must be resynchronised with the standby database by running command:
The command only needs to run once. After this command, Dbvisit Standby can be run as normal: