Oracle Recovery Manager

Oracle Recovery Manager

A complete high availability and disaster recovery strategy requires dependable data backup, restore, and recovery procedures. Oracle Recovery Manager (RMAN), a command-line and Enterprise Manager-based tool, is the Oracle-preferred method for efficiently backing up and recovering your Oracle database. RMAN is designedto work intimately with the server, providing block-level corruption detection during backup and restore. RMAN optimizes performance and space consumption during backup with file multiplexing and backup set compression, and integrates with leading tape and storage media products via the supplied Media Management Library (MML) API. RMAN takes care of all underlying database procedures before and after backup or restore, freeing dependency on OS and SQL*Plus scripts. It provides a common interface for backup tasks across different host operating systems, and offers features not available through user-managed methods, such as parallelization of backup/recovery data streams, backup files retention policy, and detailed history of all backups.

RMAN ClientRMAN is a command-line-oriented database client, much like SQL*Plus, with its own command syntax. From the RMAN client you can issue RMAN commands and SQL statements to perform and report on backup and recovery operations. RMAN can take interactive input or read input from plain text files (called command files). RMAN then communicates with one or more server processes on the target database server which actually perform the work. You can also access RMAN through the Enterprise Manager (refer to Oracle Enterprise Manager Administrator’s Guide for more details). RMAN RepositoryRMAN maintains metadata about the target database and its backup and recovery operations in the RMAN repository. Among other things, RMAN stores information about its own configuration settings, the target database schema, archived redo logs, and all backup files on disk or tape. RMAN’s LIST, REPORT, and SHOW commands display RMAN repository information. RMAN repository data is always stored in the control file of the target database. The CONTROL_FILE_RECORD_KEEP_TIME initialization parameter controls how long backup records are kept in the control file before those records are re-used to hold information about morerecent backups. The repository can also be kept in a recovery catalog, a separate database that keeps historical data on backup activities much longer than the control file and preserves backup information if the control file is lost.

Recovery CatalogIn addition to RMAN repository records, the recovery catalog can also hold RMAN stored scripts, sequences of RMAN commands for common backup tasks. Centralized storage of scripts in the recovery catalog can be more convenient than working with command files. For more information on the recovery catalog see Oracle Database Backup and Recovery Advanced User’s Guide. Media ManagersTo access sequential media devices like tape libraries, RMAN uses third-party media management software. A media manager controls these devices during backup and recovery, managing the loading, labeling and unloading of media, among other functions. Oracle Corporation’s Backup Solutions Program (BSP) works with vendors to help them produce media management software for their devices. For enterprises that already use media management software in their enterprise, many of those software products can be directly integrated with RMAN. Contact your media management software vendor for details about whether they participate in the BSP and have an RMAN-compatible media management layer.

Backup Set EncryptionBackup security is vital to the well-being of any company. Backups should only be able to be opened and read by their creators. With Oracle Database 10gR2, backup sets made to disk can now be encrypted, for the whole database or particular tablespaces, using the new CONFIGURE ENCRYPTION FOR [DATABASE | TABLESPACE …] option. Dynamic Channel Allocation for RAC EnvironmentsBy configuring the PARALLELISM parameter, RMAN will dynamically allocate the specified number of channels across all active RAC nodes, to perform the backup or restore operation. RMAN utilizes Oracle Clusterware (formerly known as Cluster Ready Services) to allocate channels to the least loaded nodes, to perform the operations. In this way, the overall backup or restore workload can be distributed across the RAC nodes more efficiently.Database Control allows DBAs to view all backup jobs by date range and backup type (e.g. full, datafile, archive log), along with their status (e.g. « completed », « completed with warnings »), input and output sizes, and output rate. Each backup job can be further drilled down to review input files and output backup sets/image copies, their sizes, and compression ratio (if enabled).