Managing UNDO, Temporary and Redo logs in RAC Environment

Reader Mode

In the oracle RAC Environment, each instance store transaction undo data in its dedicated undo Tablespace. We can set the undo Tablespace for each instance by setting the undo_tablespace parameter and undo_management to be the same across all the instances.

Example:

.undo_tablespace=undo_tbs1

.undo_tablesapce=undo_tbs2

Managing Temporary Tablespace

In an RAC environment, a user will always use the same assigned temporary Tablespace irrespective of the instance being used. Each instance creates a temporary segment in the temporary Tablespace it is using. If an instance is running a big sort operation requires a large temporary tablesapce , it can reclaim the space used by other instance’s temporary segments in that tablesapce.

Main Point:

All instance share the same temporary Tablespace

Size should be at least equal to the concurrent maximum requirement of the entire instance.

Administrating Online redologs

Each instance has exclusive write access to its own online redolog files. An instance can read another instance current on line redologs file to perform instance recovery it that instance has terminated abnormally. Online redologs file needs to be located on a shared storage device and can not be on a local node.

How to Enable Archiving in the RAC Environment

Step 1 Log in Node1.

Step 2 set cluster_database=false in parameter file.

Step 3 shut down all the instances.

Srvctl stop database –d

Step 4 mount the database

SQL> startup mount

Step 5 Enable Archiving

SQL> alter database archivelog;

Step 6 Change cluser_database=true in parameter file

Step 7 Shutdown the instance

SQL> shutdown immediate

Step 8 Start all the instance.

Scrvctl start database –d

How to Enable Archiving in the RAC Environment

Step 1 log in node 1

Step 2 Verify that the database is running in Archive log mode.

Step 3 Set parameter cluster_database =false

SQL> alter system set cluster_database=falce scope=spfile sid=’prod1’

Step 4 set parameter DB_RECOVERY_FILE_DEST_SIZE and DB_RECOVERYU_FILE_DEST

SQL> alter system set DB_RECOVERY_FILE_DEST_SIZE=200M scope=spfile;

SQL> alter system set DB_RECOVERY_FILE_DEST=/dev/rdsk/c0d3s1 scope=spfile;

Step 5 Shut down all instance.

# srvctl stop database –d

Step 6 Mount the database

SQL> statup mount

Step 7 Enable the flashback.

SQL> alter database flashback on;

Step 8 Set parameter cluster_database = true

SQL> alter system set cluster_database=falce scope=spfile sid=’prod1’

Step 9 Shutdown instance

SQL> shutdown

Step 10 Start all instance

$ srvctl start database –d >db_name>

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