|Oracle® Data Guard Concepts and Administration
11g Release 1 (11.1)
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This preface describes the new features added to Oracle Data Guard in release 11.1 and provides links to additional information. The features and enhancements described in this preface were added to Oracle Data Guard in 11g Release 1 (11.1). The new features are described under the following main areas:
The following enhancements to Oracle Data Guard in 11g Release 1 (11.1) improve ease-of-use, manageability, performance, and include innovations that improve disaster-recovery capabilities:
Compression of redo traffic over the network in a Data Guard configuration
This feature improves redo transport performance when resolving redo gaps by compressing redo before it is transmitted over the network.
See Also:"COMPRESSION" attribute
Redo transport response time histogram
V$REDO_DEST_RESP_HISTOGRAM dynamic performance view contains a histogram of response times for each
SYNC redo transport destination. The data in this view can be used to assist in the determination of an appropriate value for the
n NET_TIMEOUT attribute.
See Also:"NET_TIMEOUT" attribute.
Faster role transitions
Strong authentication for redo transport network sessions
Redo transport network sessions can now be authenticated using SSL. This provides strong authentication and makes the use of remote login password files optional in a Data Guard configuration.
Simplified Data Guard management interface
The SQL statements and initialization parameters used to manage a Data Guard configuration have been simplified through the deprecation of redundant SQL clauses and initialization parameters.
Chapter 16, "SQL Statements Relevant to Data Guard" for information about which statements have had clauses deprecated
Oracle Database Reference for information about deprecated attributes of the
You can now find the
DB_UNIQUE_NAME of the primary database from the standby database by querying the new
PRIMARY_DB_UNIQUE_NAME column in the
V$DATABASE view. Also, Oracle Data Guard release 11g ensures each database's
DB_UNIQUE_NAME is different. After upgrading to 11g, any databases with the same
DB_UNIQUE_NAME will not be able to communicate with each other.
Use of physical standby database for rolling upgrades
A physical standby database can now take advantage of the rolling upgrade feature provided by a logical standby. Through the use of the new
KEEP IDENTITY clause option to the SQL
ALTER DATABASE RECOVER TO LOGICAL STANDBY statement, a physical standby database can be temporarily converted into a logical standby database for the rolling upgrade, and then reverted back to the original configuration of a primary database and a physical standby database when the upgrade is done.
Heterogeneous Data Guard Configuration
This feature allows a mix of Linux and Windows primary and standby databases in the same Data Guard configuration.
Note:Also, see the "What's New" preface in Oracle Data Guard Broker for details about the enhanced broker-based management framework, including:
Fast-start failover for maximum performance mode in a Data Guard configuration
User-configurable events to trigger fast-start failover in a Data Guard configuration
The ARCH redo transport mode has been deprecated
The ARCH redo transport mode has been deprecated and will be desupported in a future release. Oracle recommends that you switch to the ASYNC transport mode if you are currently using the ARCH transport mode. The ASYNC transport mode is superior to the ARCH transport mode in all respects, and is the new default transport mode.
The following list summarizes the new features that are specific to Redo Apply and physical standby databases in Oracle Database 11g Release 1 (11.1):
Real-time query capability of physical standby
This feature makes it possible to query a physical standby database while Redo Apply is active.
See Also:Section 9.2, "Opening a Physical Standby Database" for more information about how an open physical standby database can continue to receive and apply redo data from a primary database
A snapshot standby database is new type of updatable standby database that provides full data protection for a primary database.
Lost-write detection using a physical standby
A "lost write" is a serious form of data corruption that can adversely impact a database. It occurs when an I/O subsystem acknowledges the completion of a block write in the database, while in fact the write did not occur in the persistent storage. This feature allows a physical standby database to detect lost writes to a primary or physical standby database.
See Also:Section 13.6, "Recovering From Lost-Write Errors on a Primary Database" for an example of lost-write recovery, and Oracle Database Backup and Recovery User's Guide for information about enabling lost-write detection
Improved Integration with RMAN
A number of enhancements in RMAN help to simplify backup and recovery operations across all primary and physical standby databases, when using a catalog. Also, you can use the RMAN
DUPLICATE command to create a physical standby database over the network without a need for pre-existing database backups.
The following list summarizes the new features for SQL Apply and logical standby databases in Oracle Database 11g Release 1 (11.1):
Support for additional object datatypes and PL/SQL package support
XML stored as
Support for additional PL/SQL Package
DBMS_RLS (row level security or Virtual Private Database)
Support Transparent Data Encryption (TDE)
Data Guard SQL Apply can be used to provide data protection for the primary database with Transparent Data Encryption enabled. This allows a logical standby database to provide data protection for applications with advanced security requirements.
Dynamic setting of Data Guard SQL Apply parameters
You can now configure specific SQL Apply parameters without requiring SQL Apply to be restarted. Using the
DBMS_LOGSTDBY.APPLY_SET package, you can dynamically set initialization parameters, thus improving the manageability, uptime, and automation of a logical standby configuration.
In addition, the
APPLY_UNSET subprograms include two new parameters:
DBMS_LOGSTDBYPL/SQL package in the Oracle Database PL/SQL Packages and Types Reference
Enhanced RAC switchover support for logical standby databases
When switching over to a logical standby database where either the primary database or the standby database is using Oracle RAC, the
SWITCHOVER command can be used without having to shut down any instance, either at the primary or at the logical standby database.
Enhanced DDL handling in Oracle Data Guard SQL Apply
SQL Apply will execute parallel DDLs in parallel (based on availability of parallel servers).
Use of the PL/SQL DBMS_SCHEDULER package to create Scheduler jobs on a standby database
Scheduler Jobs can be created on a standby database using the PL/SQL
DBMS_SCHEDULER package and can be associated with an appropriate database role so that they run when intended (for example, when the database is the primary, standby, or both).