much greater
detail in Chapter 11.
Recovery Manager
Typical kinds of backups include complete database backups (the most common type), tablespace backups, datafile backups, control file backups, and archivelog backups. Oracle8 introduced the Recovery Manager (RMAN) for the server-managed backup and recovery of the database, leveraging a Recovery Catalog stored in the database. RMAN can automatically locate, back up, restore, and recover datafiles, control files, and archived redo logs. Since Oracle9 i , RMAN can restart backups and restore and implement recovery window policies when backups expire. Oracle Enterprise Manager provides a GUI-based interface to RMAN. Oracle Enterprise Manager 10 g introduced an improved job scheduler that can be used with RMAN for managing automatic backups to disk.
Incremental backup and recovery
RMAN can perform incremental backups of Enterprise Edition databases. Incremental backups will back up only the blocks modified since the last backup of a datafile, tablespace, or database; thus, they’re smaller and faster than complete backups.
RMAN can also perform point-in-time recovery, which allows the recovery of data until just prior to an undesirable event (such as the mistaken dropping of a table).
24
|
Chapter 1: Introducing Oracle
Oracle Secure Backup
Various media-management software vendors leverage Oracle’s RMAN, but starting with Oracle Database 10 g , the database also includes an entry-level tape storage management solution of its own known as Oracle Secure Backup XE. Optionally, Oracle offers an enterprise-class backup solution simply named Oracle Secure Backup.
Database Availability
Database availability depends upon the reliability and management of the database, the underlying operating system, and the specific hardware components of the system. Oracle has improved availability by reducing backup and recovery times by:
• Providing online and parallel backup and recovery
• Improving the management of online data through range partitioning
• Leveraging hardware capabilities for improved monitoring and failover The relevant features are described in the following subsections.
Partitioning option
Oracle introduced partitioning as an option with Oracle8 to provide a higher degree of manageability and availability. Youcan take individual partitions offline for maintenance while other partitions remain available for user access. In data warehousing implementations, partitioning is sometimes used to implement rolling windows based on date ranges. Other partitioning types include hash partitioning (used to divide data into partitions using a hashing function and providing an even distribution of data) and list partitioning (enabling partitioning of data based on discrete values such as geography). Starting with Oracle Database 11 g , interval partitioning can also be used to automatically create new fixed ranges as needed during data insertions.
Many of these partitioning types can be used in combination as “composite” partitions. Examples of composite partitions in Oracle Database 11 g include range-range, range-hash, range-list, list-range, list-hash, and list-list.
Data Guard
Oracle first introduced a standby database feature in Oracle 7.3. The standby database provides a copy of the production database to be used if the primary database is lost—for example, in the event of primary site failure or during routine maintenance. Primary and standby databases may be geographically separated. The standby database is created from a copy of the production database and updated through the application of archived redo logs generated by the production database. Data Guard, Database Management Features
|
25
first introduced in Oracle9 i , fully automates this process; previously, you had to manually copy and apply the logs. Agents are deployed on both the production and standby database, and a Data Guard Broker coordinates commands. A single Data Guard command
detail in Chapter 11.
Recovery Manager
Typical kinds of backups include complete database backups (the most common type), tablespace backups, datafile backups, control file backups, and archivelog backups. Oracle8 introduced the Recovery Manager (RMAN) for the server-managed backup and recovery of the database, leveraging a Recovery Catalog stored in the database. RMAN can automatically locate, back up, restore, and recover datafiles, control files, and archived redo logs. Since Oracle9 i , RMAN can restart backups and restore and implement recovery window policies when backups expire. Oracle Enterprise Manager provides a GUI-based interface to RMAN. Oracle Enterprise Manager 10 g introduced an improved job scheduler that can be used with RMAN for managing automatic backups to disk.
Incremental backup and recovery
RMAN can perform incremental backups of Enterprise Edition databases. Incremental backups will back up only the blocks modified since the last backup of a datafile, tablespace, or database; thus, they’re smaller and faster than complete backups.
RMAN can also perform point-in-time recovery, which allows the recovery of data until just prior to an undesirable event (such as the mistaken dropping of a table).
24
|
Chapter 1: Introducing Oracle
Oracle Secure Backup
Various media-management software vendors leverage Oracle’s RMAN, but starting with Oracle Database 10 g , the database also includes an entry-level tape storage management solution of its own known as Oracle Secure Backup XE. Optionally, Oracle offers an enterprise-class backup solution simply named Oracle Secure Backup.
Database Availability
Database availability depends upon the reliability and management of the database, the underlying operating system, and the specific hardware components of the system. Oracle has improved availability by reducing backup and recovery times by:
• Providing online and parallel backup and recovery
• Improving the management of online data through range partitioning
• Leveraging hardware capabilities for improved monitoring and failover The relevant features are described in the following subsections.
Partitioning option
Oracle introduced partitioning as an option with Oracle8 to provide a higher degree of manageability and availability. Youcan take individual partitions offline for maintenance while other partitions remain available for user access. In data warehousing implementations, partitioning is sometimes used to implement rolling windows based on date ranges. Other partitioning types include hash partitioning (used to divide data into partitions using a hashing function and providing an even distribution of data) and list partitioning (enabling partitioning of data based on discrete values such as geography). Starting with Oracle Database 11 g , interval partitioning can also be used to automatically create new fixed ranges as needed during data insertions.
Many of these partitioning types can be used in combination as “composite” partitions. Examples of composite partitions in Oracle Database 11 g include range-range, range-hash, range-list, list-range, list-hash, and list-list.
Data Guard
Oracle first introduced a standby database feature in Oracle 7.3. The standby database provides a copy of the production database to be used if the primary database is lost—for example, in the event of primary site failure or during routine maintenance. Primary and standby databases may be geographically separated. The standby database is created from a copy of the production database and updated through the application of archived redo logs generated by the production database. Data Guard, Database Management Features
|
25
first introduced in Oracle9 i , fully automates this process; previously, you had to manually copy and apply the logs. Agents are deployed on both the production and standby database, and a Data Guard Broker coordinates commands. A single Data Guard command
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