Oracle 12c New Features 07 – RMAN Enhancements
The following sections describe improvements to Recovery Manager (RMAN).
Active Database Duplication Enhancements
Active DUPLICATE uses a network-enabled restore method that is run on the auxiliary database to clone the source database. This is in contrast to the image copy-based approach that was run on the source database in previous releases. Active DUPLICATE supports the SECTION SIZE option to divide data files into subsections that are restored in parallel across multiple channels on the auxiliary database. Active DUPLICATE supports compression during the restore phase.
The benefits of this new feature include:
1. Reduce active duplicate time for databases with large data files by more evenly spreading out the restore workload across multiple channels on the auxiliary database.
2. Reduce active duplicate time by more efficiently using network bandwidth using compression during data transfer operations.
Cross-Platform Backup and Restore
BACKUP and RESTORE commands feature new options to create a cross-platform compatible backup and to restore the same on a different platform.
This feature reduces operational complexity using cross-platform transportable tablespace and cross-platform transportable database methods to migrate data between platforms.
This feature disables automatic opening of a recovered clone database so that you can perform any database setting changes before using the NOOPEN option. For example, you may want to modify block change tracking or Flashback Database settings before opening the clone database. This feature is also useful for upgrade scenarios where the database must not be open with RESETLOGS prior to running upgrade scripts.
These enhancements provide additional flexibility during DUPLICATE and expand its use for upgrade scenarios. For example, the NOOPEN option allows DUPLICATE to create a new database as part of an upgrade procedure and leaves the database in a state ready for opening in upgrade mode and subsequent execution of upgrade scripts.
Multisection Image Copies
Image copies can be taken with the SECTION SIZE option to divide data files into subsections that can be backed up in parallel across multiple channels. This feature reduces image copy creation time for large data files which is especially beneficial in Exadata environments.
This can also reduce completion time for non-backup use cases. For example, copying a file as part of a transportable tablespace procedure or creating a clone with active duplicate.
Multisection Incremental Backups
Incremental backups can be taken with the SECTION SIZE option to divide data files into subsections that can be backed up in parallel across multiple channels. This reduces the incremental backup time for large data files which is especially beneficial in Exadata and cloud environment backups.
RESTORE operations can copy data files from one database to another (for example, a physical standby database to a primary database) over the network. Network-enabled restore also supports compression and multisection options.
The RESTORE operation reduces data file copy time from one database to another by reducing data transfer sizes and by better parallelizing restore workload for large data files across multiple channels.
RMAN Command-Line Interface Enhancements
Recovery Manager (RMAN) command-line interface has been enhanced to:
1. Run SQL as-is at the command line, no longer requiring the SQL command.
2. Support SELECT statements.
3. Support the DESCRIBE command on tables and views.
These enhancements provide better ease-of-use when running SQL in an RMAN session.
Storage Snapshot Optimization
Backup mode can induce additional system and I/O overhead due to writing whole block images into redo, in addition to increasing procedural complexity in large database environments. A third-party storage snapshot that meets the following requirements can be taken without requiring the database to be placed in backup mode:
1. Database crash is consistent at the point of the snapshot.
2. Write ordering is preserved for each file within a snapshot.
3. Snapshot stores the time at which a snapshot is completed.
4. A new RECOVER command keyword, SNAPSHOT TIME, is introduced to recover a snapshot to a consistent point, without any additional manual procedures for point-in-time recovery needs.
The overhead consists of logging additional redo and performing a complete database checkpoint.
Table-Level Recovery From Backups
Recovery Manager (RMAN) can restore and recover a table or set of tables from existing backups on disk or tape with the new RECOVER TABLE option.
This option reduces time and disk space to recover a table or set of tables from an existing backup versus manually restoring and recovering the required tablespaces to a separate disk location, then exporting the desired tables and importing them to the original database.