Database Reference
In-Depth Information
Upon determining the thread number, redo groups, and undo tablescapes for the additional instances, now it is
time to remove them from the database. The following set of SQL statements will achieve this:
SQL> ALTER DATABASE disable THREAD <thread_number>;
SQL> ALTER DATABASE drop logfile group <group_number>;
SQL> DROP TABLESPACE <undo_instance_specific> including contents and datafiles;
Assuming that a RAC database with three instances restored to a single-instance database, you need to follow the
preceding procedure for instances 2 and 3 in order to have a clean single-instance database.
Configure RAC Standby Database
In the following example, we demonstrate how to configure a standby RAC database with two instances to a
RAC primary database with two instances. The primary RAC database name used in the context is RONDB, and
the standby RAC database is named RONDBS. Prior to getting into the real action, we will assume that the same
version, platform, Clusterware, and Oracle RBDMS binaries are configured and operational at the standby location.
The objective is to explain the procedure to set up a standby RAC database; the data guard configuration and the
switchover/failover mechanism, however, is not part of our objective.
Once the standby environment is ready, run through the following tasks on the standby site:
•
Create and mount necessary ASM DISKGROUPS across the nodes on which RAC standby
instances are going to be placed.
•
Configure a listener for the standby instances and a TNS connection pointing to the primary
database instance on the standby nodes.
•
After preparing SPFILE and the password file, and creating all necessary directory structures,
start up the standby instance in NOMOUNT state:
SQL> STARTUP NOMOUNT.
•
Initiate the active standby database configuration procedure from the standby instance RMAN:
# rman connect target sys/password@prim auxiliary /
RMAN> duplicate target database for standby from active database
spfile
parameter_value_convert 'RONDB','RONDBS'
set db_unique_name='RONDBS'
set fal_client='PRIM'
set fal_server='STDBY'
set standby_file_management='AUTO'
set log_archive_config='dg_config=(RONDBS,RONDB)'
set log_archive_dest_1='service=RONDBS ASYNC
valid_for=(ONLINE_LOGFILE,PRIMARY_ROLE) db_unique_name=RONDBS';
•
Once the standby database is successfully configured, create standby redo logs on the standby
instance of the same number (plus one additional group) and the same size as the primary
database redo logs. It is highly recommended to have an additional standby redo group for
each instance, in contrast to the primary database instance redo groups count. Presume that a
primary instance has three redo groups and each redo member is sized 100M; therefore, we will
have four standby redo groups for each standby instance with the same redo log member size.
