Oracle RAC

Owned by Kevin Wu
Last updated: Oct 19, 2023 by Manuel Pereira
2 min read

With Oracle Real Application Clusters (RAC) it is possible to use two database instances at the same time, when extracting data from the database.

The settings assume that an existing Oracle Instance is ready for use.

  1. Install Oracle RAC, create a database with shared storage on the cluster nodes and listeners according to normal Oracle RAC procedures.

  2. Modify the install.xml file to include the SID of one of the instances of the RAC cluster and modify other obvious information (such as the location of the shared storage place of the database files and the Oracle installation).

  3. Modify and run Oracle scripts.

    1. Modify the oracle_create_instance.sh file.

      The following passage in the oracle_create_instance.sh file should be commented out. It is, however, important to make sure that listeners are running correctly for RAC instances/services since modification of the script causes it to not check for the presence of running listeners.

      # Make sure that the listener is up for our instance. # It is not really needed in this script but it will be # necessary in the installer. # lsnrctl status | grep "Instance \"${ORACLE_SID}\"" > /dev/null # # if [ $? -ne 0 ] ; then # echo "The listener for $ORACLE_SID is not running, abort!" 1>&2 # exit 1 # fi

       

    2. Modify oracle_create.sql.

      The following passage should be commented out. This makes the script create tables and users in the RAC instances, rather than create a new database/instance.

      -- Create the database -- prompt Creating database -- CREATE DATABASE orac1 -- DATAFILE '/opt/oradata/orac/mz/ts_orac1_system.dbf' -- SIZE 250M REUSE AUTOEXTEND OFF -- sysaux datafile '/opt/oradata/orac/mz/ts_orac1_sysaux.dbf' -- size 100M autoextend off -- UNDO TABLESPACE MZ_UNDO_TS_01 -- DATAFILE '/opt/oradata/orac/mz/ts_orac1_undo01.dbf' -- SIZE 125m REUSE AUTOEXTEND OFF -- LOGFILE -- group 1 ('/opt/oradata/orac/mz/ts_orac1_log01.log') size 15M, -- group 2 ('/opt/oradata/orac/mz/ts_orac1_log02.log') size 15M, -- group 3 ('/opt/oradata/orac/mz/ts_orac1_log03.log') size 15M, -- group 4 ('/opt/oradata/orac/mz/ts_orac1_log04.log') size 15M;

       

      When running the *.sql scripts, the original file $ORACLE_HOME/dbs/init*.ora (* = instance name) is replaced with a new .ora file. The original file has to be restored, hence the file created by should not be used. The easiest way to restore the init<instance>.ora file is to copy it from the second node, since they should be identical on both hosts. An example of an init<instance>.ora is shown next:

      oracga1.local_listener="(address=(protocol=tcp) (host=10.0.0.111)(port=1521))" oracga2.local_listener="(address=(protocol=tcp) (host=10.0.0.112)(port=1521))" SPFILE='+ORAC50/oracga/spfileoracga.ora'


      The three occurrences of create tablespace should also be changed. Remove the path after DATAFILE and remove REUSE before AUTOEXTEND, so it looks like this:

       

    3. Run oracle_create_instance.sh 

      Â