Oracle media recovery or redo apply is a fundamental element of Oracle Maximum Availability Architecture (Oracle MAA) environments. Media recovery occurs when one or more data files or the control files are restored from a previous backup or when using Data Guard Redo Apply for physical standby databases.

What is difference between redo apply and real time apply?

However, if you use a standby redo log, you can optionally enable real time apply, which allows Data Guard to recover redo data from the current standby redo log as it is being filled by the RFS process. This facility of real time apply is a new feature introduced in Oracle database 10g.

What is Oracle dataguard replication?

When to use Active Data Guard: Active Data Guard provides the best data protection and availability for Oracle Database in the simplest most economical manner by maintaining an exact physical replica of the production database at a remote location that is open read-only while replication is active.

What does Oracle dataguard do?

Oracle Data Guard ensures high availability, data protection, and disaster recovery for enterprise data. Data Guard provides a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable production Oracle databases to survive disasters and data corruptions.

What is Data Guard lag apply?

APPLY LAG – Apply lag is a measure of the degree to which the data in a standby database lags behind the data in the primary database, due to delays in propagating and applying redo to the standby database.

What is the difference between Oracle Data Guard and Active Data Guard?

The main difference between Oracle Data Guard and Active Data Guard is that Oracle Data Guard is an extension to the Oracle RDBMS and provides data availability and protection while Active Data Guard is an extension of Oracle Data Guard and improves the production database performance for critical transactions.

How do I check the status of my redo application?

Query the physical standby database to monitor Redo Apply and redo transport services activity at the standby site. SELECT PROCESS, STATUS, THREAD#, SEQUENCE#, BLOCK#, BLOCKS FROM V$MANAGED_STANDBY; To determine if real-time apply is enabled, query the RECOVERY_MODE column of the V$ARCHIVE_DEST_STATUS view.

What is meant by Active Data Guard?

Active Data Guard enables read-only access to a physical standby database while Redo Apply is active. Queries and reports can be offloaded from the production system to a synchronized physical standby database – all queries at the standby database return up-to-date results.

What is the difference between Oracle RAC and Data Guard?

What is the difference between Oracle RAC and Data Guard? RAC has one database and several instances associates with it, but data guard has several databases (one primary and others standby databases). RAC is the recommended solution for instance, software and hardware level failures. … RAC can have maximum of 100 nodes.

How is Active Data Guard license?

Data Guard is a feature of the Oracle Database Enterprise Edition itself and does not require separate licensing. On the other hand, Active Data Guard is a so-called Oracle Database Enterprise Edition Option and as such requires separate licensing.

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What is Oracle Data Guard 19c?

Data Guard Physical Standby Setup Using the Data Guard Broker in Oracle Database 19c. Data Guard is the name for Oracle’s standby database solution, used for disaster recovery and high availability.

What is Active Data Guard in Oracle 11g?

Oracle Active Data Guard, an option of Oracle Database 11g Enterprise Edition is a simple, high performance solution that protects your Oracle Database against planned and unplanned downtimes, by allowing you to offload resource workloads from your production database to one or more synchronized standby databases.

How do I know if dataguard is in protected mode?

SQL> alter database set standby database to maximize {AVAILABILITY | PERFORMANCE | PROTECTION}; SQL> alter database open; 4. To confirm the change in protection mode, query v$database on the primary.

How do I check my primary standby database status?

Following command will help to check the Standby is sync with Primary Database in Oracle Dataguard Environment. select thread#, max(sequence#) “Last Standby Seq Applied” from v$archived_log val, v$database vdb where val. resetlogs_change# = vdb.

How do you check if Data Guard is enabled in Oracle?

1. # select database_role from v$database; PHYSICAL STANDBY.
2. # select protection_mode from v$database; MAXIMUM PERFORMANCE.
3. # select db_unique_name from v$dataguard_config. PRD.
4. # standby_file_management = AUTO.
5. # select * from v$dataguard_status; Services Informational 0 1 0 NO.

What is V Archived_log?

V$ARCHIVED_LOG displays archived log information from the control file, including archive log names. An archive log record is inserted after the online redo log is successfully archived or cleared (name column is NULL if the log was cleared).

How do I get rid of Recover auto standby database?

The AUTOMATIC option automatically generates the name of the next archived redo log file needed to continue the recovery operation. Cancel recovery after the Oracle database server has applied the available logs, by executing the following statement (or typing CTRL+C): SQL> CANCEL Media recovery cancelled.

What is open mount and Nomount in Oracle database?

When the database is nomount state, then database instance has been started using initialization file. Thus processes started and memory allocated. In Mount: The instance started and control file is opened. The control file is read but it’s contents are not validated.

How do I enable Active Data Guard in physical standby database?

1. Invoke DGMGRL and connect as SYS. Enter <your password> for SYS. …
2. Invoke SQL*Plus and connect to your standby database as SYSDBA. …
3. Invoke DGMGRL and connect as SYS. …
4. Invoke SQL*Plus and connect to your standby database as SYSDBA. …
5. Invoke SQL*Plus and connect to your primary database as SYSDBA.

What is snapshot standby?

What Is a Snapshot Standby Database? A snapshot standby database is a fully updateable standby database created by converting a physical standby database into a snapshot standby database. A snapshot standby database receives and archives, but does not apply, redo data from a primary database.

Why do we need Oracle RAC?

The main aim of Oracle RAC is to implement a clustered database to provide performance, scalability and resilience & high availability of data at instance level.

What is Oracle RAC One Node?

Oracle Real Application Clusters (RAC) One Node is an option to the Oracle Database Enterprise. Edition that was introduced with Oracle Database 11g Release 2. It provides enhanced high availability. for single instance Oracle Databases, protecting them from both, planned and unplanned downtime.

How do I open Active Data Guard?

1. Step1: Check standby database recovery mode.
2. Step2: Stop Recovery.
3. Step3: Enable Active Data Guard.
4. Step4: Check Database Role.
5. Step5: Start Recovery.
6. Step6: Check Database Role After Recovery.
7. Step7: Try to login from third party clients (TOAD, SQL Developer).

How much does Oracle Data Guard cost?

Active Data Guard is not free, however. Active Data Guard carries a list price of $11,500 USD, and both the primary and standby databases must be licensed if they reside on different physical servers.

How do you open database in read only with apply?

1. Cancel log apply services: SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
2. Open the database for read-only access: SQL> ALTER DATABASE OPEN READ ONLY;

What is Data Guard in OCI?

Oracle Data Guard maintains the standby database by transmitting and applying redo data from the primary database. If the primary database becomes unavailable, then you can use Oracle Data Guard to switch or fail over the standby database to the primary role.

What are the 12c dataguard new features?

Other minor features that were introduced in Oracle Active Data Guard 12c: … You can now use sequences in a Data Guard environment. You no longer need to shut down all other primary database instance if you need to switchover from an Oracle Real Application Clusters primary database to a physical standby.

What are standby redo logs used for?

Standby redo logs are used to store data received from another database or the primary data source. Standby redo logs are present at the destination database end.

Where do I put standby redo logs?

To create new standby redo log file groups and members, you must have the ALTER DATABASE system privilege. The standby database begins using the newly created standby redo data the next time there is a log switch on the primary database.

How do I get rid of standby redo logs?

1. Enviroment.
2. SET STANDBY_FILE_MANAGEMENT=’MANUAL’
3. Drop SRL On Standby.
4. SET STANDBY_FILE_MANAGEMENT=’AUTO’
5. Enable MRP.
6. Enviroment. …
7. SET STANDBY_FILE_MANAGEMENT=’MANUAL’ …
8. Drop SRL On Standby.

What are different protection modes in dataguard?

Oracle Data Guard provides three protection modes: maximum availability, maximum performance, and maximum protection.