Question

Oracle Database 11g: New Features in RMAN

Answer 1

Advice on recovery

To find out failure...

RMAN> list failure;

To get the advice on recovery

RMAN> advise failure;

Recovery Advisor generates a script that can be used to repair the datafile or resolve the issue. The script does all the work.

To verify what the script actually does ...

RMAN> repair failure preview;

Now execute the actual repair by issuing...

RMAN> repair failure;


Proactive Health Checks

In Oracle Database 11g, a new command in RMAN, VALIDATE DATABASE, can check database blocks for physical corruption.

RMAN> validate database;

Parallel backup of the same datafile.

In 10g each datafile is backed by only one channel. In Oracle Database 11g RMAN, the multiple channels can backup one datafiles parallel by breaking the datafile into chunks known as "sections." 

Answer 2

Optimized backup of undo tablespace.

In 10g, when the RMAN backup runs, it backs up all the data from the undo tablespace. But during recovery, the undo data related to committed transactions are no longer needed.
In Oracle Database 11g, RMAN bypasses backing up the committed undo data that is not required in recovery. The uncommitted undo data that is important for recovery is backed up as usual. This reduces the size and time of the backup.

Improved Block Media Recovery Performance

If flashback logs are present, RMAN will use these in preference to backups during block media recovery (BMR), which can significantly improve BMR speed.

Block Change Tracking Support for Standby Databases

Block change tracking is now supported on physical standby databases, which in turn means fast incremental backups are now possible on standby databases.

Answer 3

Faster Backup Compression

RMAN now supports the ZLIB binary compression algorithm as part of the Oracle Advanced Compression option. The ZLIB algorithm is optimized for CPU efficiency, but produces larger zip files than the BZIP2 algorithm available previously, which is optimized for compression.

Archived Log Deletion Policy Enhancements

The archived log deletion policy of Oracle 11g has been extended to give greater flexibility and protection in a Data Guard environment. The Oracle 10g and Oracle 11g syntax is displayed below.

# Oracle 10g Syntax.
CONFIGURE ARCHIVELOG DELETION POLICY {CLEAR | TO {APPLIED ON STANDBY | NONE}}
# Oracle 11g Syntax.
ARCHIVELOG DELETION POLICY {CLEAR | TO {APPLIED ON [ALL] STANDBY |BACKED UP integer TIMES TO DEVICE TYPE deviceSpecifier |NONE | SHIPPED TO [ALL] STANDBY}[ {APPLIED ON [ALL] STANDBY | BACKED UP integer TIMES TO DEVICE TYPE deviceSpecifier |NONE | SHIPPED TO [ALL] STANDBY}]...}

The extended syntax allows for configurations where logs are eligible for deletion only after being applied to, or transferred to, one or more standby database destinations.