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  • November 14, 2014

Oracle Database 12c: RMAN Enhancements

Sridhar Ranganathan
Sr. Principal Product Manager

Hello folks,



In this blog, I am going to provide an overview of new Oracle Recovery Manager (RMAN) features that were introduced in Oracle Database 12c. 


As an integral part of Oracle Database, RMAN offers a complete and integrated backup and recovery solution to address a variety of operations – from routine to very complex.  RMAN has steadily evolved over the past 16 years – mainly because Oracle has listened to our customers. We’ve continued to incorporate many valuable enhancements, including the following features that were introduced with Oracle Database 12.1.0.1.

 1. Fine grained recovery

With Oracle Database 12c, you can use a simple RECOVER TABLE command to perform a point-in-time recovery of a table/partition without having to go through a manual point-in-time recovery process. This command automatically performs the following steps: creation of the auxiliary instance, table recovery, exporting of the object, and importing it into the production database.

2. Support for multitenant databases

Oracle Database 12c offers this unprecedented consolidation feature called Oracle Multitenant. This capability simplifies database consolidation and management by enabling many individual pluggable databases (PDBs) to be “plugged-into” and supported within a container database (CDB).  Data protection is greatly simplified because you can perform backup and recovery at the CDB level, which includes and protects all the associated PDBs. For additional flexibility, you can still choose to perform backup and recovery for an individual PDB or a selected group of PDBs.

3. Improved RMAN duplication (cloning) performance

Duplicating an Oracle database can be performed in many ways. Today, customers use both Oracle features such as RMAN DUPLICATE or storage-based snapshot and cloning technologies. RMAN duplication can be performed by using an existing backup or by directly duplicating the database using ACTIVE DUPLICATE.  Prior to Oracle Database 12c,  the ACTIVE DUPLICATE process used production database processes to send image copies across the network. This could be a time-consuming activity because the duplication process is directly proportional to the database size. Now, with 12c, the database duplication process has been improved, with the use of backup sets instead of image copies. As a result, the database size is relatively smaller because RMAN skips unused blocks, committed undo blocks etc. Plus, you can use compression and multi-section options for even faster duplication. Moreover, auxiliary channels from the destination site are used to PULL the backups over the network, as opposed to the PUSH method, used prior to 12c.

4. Faster recovery in a Data Guard or Active Data Guard environment

You may already be aware of some cool RMAN features that are supported with Active Data Guard – for example, direct Block Media Recovery from the standby. However, in the event of either primary or standby datafile corruption (e.g. due to media errors), the traditional recovery process would be to copy the backup over the network and perform a restore/recovery.  With Oracle Database 12c, there is a new RMAN keyword  called “FROM SERVICE” whereby you can perform restores directly from the standby or from the primary (depending on which site has issues). This command creates a backup set and streams it over the network. This new process dramatically reduces the overall recovery time.

5. Expansion of Multi-section support

Prior to Oracle Database12c, parallelizing a single data file using MULTI SECTION was only supported with a level 0 backup or a full backup set. From 12c, Multi section is now supported with incremental backups as well as image copy backups.

6. Simplified cross-platform migration

Migrating the database from one platform to another can be performed in many ways. Oracle supports both database-level migration and tablespace-level migration. Database-level migration requires the endian type to be same on the source and destination platforms. Using tablespace migration, you can migrate across platforms and across endian formats. Oracle 12c introduces new keywords - FROM PLATFORM and TO PLATFORM. Using these keywords, RMAN takes care of converting the endian-ness,  so that the overall process is simplified. Depending on the availability requirements, tablespace migration can be performed with either long downtime or reduced downtime processes.
    

a) When using a longer downtime model, you place the tablespace(s) in read-only mode, take the full backup, and restore at the destination. You also take the metadata export of the tablespace at the source and then apply at the destination. Once you’re done, the tablespaces are made readable/writable at the destination.
  

 b) When using a reduced downtime model, you can keep your source database running for a longer time by doing incremental backups to the destination. Only the last step involves the procedure mentioned in (a).

7. Separation of Duty

A new role SYSBACKUP is introduced to separate backup administrator tasks from the SYS role. You can use this administrative privilege to perform backup and recovery operations from either RMAN or from SQL*Plus.



8. SQL interface in RMAN


 Beginning with Oracle Database12c, you no longer have to switch between the SQL*Plus interface and RMAN interface. The RMAN interface now supports SQL commands so you can directly run the commands from within RMAN.



I covered these topics in my Oracle Open World 2014 RMAN presentation.  The cloud backup solution Oracle Database Backup Serviceas well as our newly introduced Zero Data Loss Recovery Appliance are also covered in this presentation.


For further details, refer to Oracle Documentation.

If you would like me to provide further technical content on any of the above RMAN features or have questions, please register your comments below.

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