RMAN, new configuration parameters in 11g

Configuration parameters define the overall environmental behavior of rman. You can set these parameters to automate things as well as define bevaviors with repect to different commands. In 11g there are two new parameters which are basically two new features. You can use the following command to list all configuration parameters with their default values.

RMAN> show all;
using target database control file instead of recovery catalog
RMAN configuration parameters for database with db_unique_name ORCL are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default
CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u01/app/oracle/product/11.2.0/dbhome_1/dbs/snapcf_orcl.f'; # default

I have highlighted both the new parameters. First one, as you may have guessed RMAN now allows you to compress the backup sets generated via rman. The configuration allows you to set the default compression algorithm which you want to use while taking backups. By default it is set to basic which you can change depending on your requirement. To see the list of algorithms available you can use the following command. Note the description column which states which algorithm is suited for what situations.

SQL> select algorithm_name,algorithm_description,is_default
  2  from V$RMAN_COMPRESSION_ALGORITHM;
ALGORITHM_NAME       ALGORITHM_DESCRIPTION  IS_
------------------------------ -------------------------------------------------- ---
BZIP2       good compression ratio  NO
BASIC       good compression ratio  YES
LOW       maximum possible compression speed  NO
ZLIB       balance between speed and compression ratio  NO
MEDIUM       balance between speed and compression ratio  NO
HIGH       maximum possible compression ratio  NO

6 rows selected.

You can change the value of parameter using the following command.

RMAN> configure compression algorithm "low";
new RMAN configuration parameters:
CONFIGURE COMPRESSION ALGORITHM 'low' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE;
new RMAN configuration parameters are successfully stored
RMAN> 

The other parameter allows you to set the archivelog deletion policy. As name suggests that this setting when set will cause automatic deletion of archivelogs. This is a very handsome feature in itself and will require another post for full details.

Enough to state is that you can set policy like delete archivelogs after two backups. RMAN will delete archive logs which have been backed up twice.