Oracle 1z0-076 Oracle Database 19c: Data Guard Administration Exam Practice Test

After a successful failover to the 'cats' database in a Data Guard configuration:

B: Sheep, being another standby database, would typically remain in the enabled state unless specifically disabled or if there was a configuration issue.

D: Dogs, which was the primary database prior to failover, will be in a disabled state as part of the failover process. Manual intervention is required to re-establish 'dogs' as a standby database or to return it to the primary role through another role transition.

E: If the configuration was in Maximum Availability mode before failover, it would remain in this mode after failover, provided all settings were properly configured and no changes were made to the protection mode.

Option A is incorrect because failover does not automatically change the protection mode to Maximum Performance. The protection mode remains as it was prior to the failover unless manually altered.

Flashback Database is a feature that allows reverting a database to a previous point in time, which is extremely useful in various Data Guard configurations:

It may be used to flash back a physical standby that receives redo from a far sync instance (C):Flashback Database can be used on a physical standby database to revert it to a past point in time, even when it is receiving redo data from a far sync instance. This can be particularly useful to recover from logical corruptions or unwanted changes.

You can use it when real-time apply is enabled in case the physical standby suffers from logical corruption (D):Even when real-time apply is enabled, which allows redo data to be applied to the standby database as soon as it is received, Flashback Database can be used to revert the physical standby database to a point in time before the logical corruption occurred.

A Physical Standby Database can indeed be converted into a Logical Standby Database, providing flexibility in a Data Guard configuration. This allows for the database to switch roles and supports SQL apply operations, enabling more granular control over the data and transactions being replicated and applied. Additionally, having a configuration with a primary database and one or more physical standby databases allows for rolling upgrades to be performed. This means that each database in the Data Guard configuration can be upgraded in a phased manner, minimizing downtime and ensuring high availability during the upgrade process​​​​.

Oracle Multi-tenant architecture and Data Guard have several interactions, but specific aspects hold true in such environments:

The Data Guard broker may be used for multi-tenant databases (B):Data Guard Broker simplifies the management and monitoring of Data Guard configurations and is fully compatible with the Oracle Multi-tenant architecture, allowing for easy management of Data Guard configurations that include multi-tenant container databases (CDBs) and their pluggable databases (PDBs).

When setting up a Data Guard Broker configuration for a primary database and its physical standby, the following prerequisites must be met:

A: Oracle Net connectivity must be defined on both the primary and standby hosts to enable the respective database instances to communicate with each other.

B: Supplemental logging is required on the primary database because it provides additional logging necessary for the standby database to be able to apply changes from the primary database accurately.

F: TheDG_BROKER_STARTparameter must be set toTRUEfor both the primary and standby database instances. This parameter is used to start the Data Guard Broker process which manages the configuration.

Options C and D are not prerequisites for creating a Data Guard Broker configuration. Additionally, while FORCE LOGGING mode (option E) is recommended as a best practice to prevent possible data inconsistencies during media recovery, it is not a strict prerequisite for creating a Data Guard Broker configuration.

Enterprise Manager Cloud Control offers comprehensive monitoring capabilities for Oracle Data Guard environments. It enables monitoring the rate at which redo is being applied on a logical standby database (A), which is crucial for ensuring that the standby database is keeping up with the changes from the primary. It also allows setting thresholds on performance metrics, such as the redo generation rate on the primary database (B), to alert administrators when values exceed critical or warning thresholds. Additionally, it provides the capability to estimate the potential data loss in the event of a disaster (E), helping in disaster recovery planning and ensuring business continuity.

Far Sync instances are a feature of Oracle Data Guard designed to support zero data loss protection over long distances:

The Data Guard Broker must be used to deploy and manage Far Sync instances (A):Data Guard Broker simplifies the deployment and management of Far Sync instances, which are an integral part of zero data loss protection configurations.

They enable standby databases to be configured at remote distances from the primary without impacting performance on the primary (C):Far Sync instances are designed to receive redo from the primary database and then forward it to a remote standby database, thereby avoiding any performance impact on the primary database itself.

In Oracle, a sequence created with theGLOBALkeyword is available and can produce values across all sessions and instances. However, a sequence created with theSESSIONkeyword is only specific to the session it was created in. When theNEXTVALis called for a sequence, it will increment according to the sequence's properties set during its creation.

Given the sequence creation statements and the actions performed:

Theasequence is global, which means it is available across the entire database, including the standby database with Real-Time Query enabled. So, when session 2 callsa.nextval, it will get the next value in the sequence, which is 21 since session 1 already retrieved 1.

Thebsequence is session-specific, so when session 2 callsb.nextval, it will get the value 1 because for this new session on the standby, this is the first time the sequence is being accessed.

Therefore, the output for session 2 will beaoutput as 21 andboutput as 1, which corresponds to Option C.

C. The LGWR (Log Writer) process is responsible for writing redo entries from the redo log buffer to the online redo log files on the primary database. This is a fundamental process in the Oracle Database architecture, ensuring that all changes made to the database are captured for purposes such as recovery, replication, and high availability.

D. Real-time apply on a logical standby database requires standby redo log files. The standby redo log files are used to store redo data received from the primary database before it is applied to the logical standby database. This enables the logical standby to apply changes as they are received, without waiting for the current redo log file to be archived.

E. Similarly, on a physical standby database, standby redo log files are used for real-time apply. They store redo data from the primary database, allowing the physical standby to apply redo data concurrently as it is received, rather than waiting for redo log files to be archived. This capability is crucial for maintaining a physical standby database that is closely synchronized with the primary database with minimal lag.

These functionalities are integral to Oracle Data Guard configurations and are not dependent on Oracle Streams or Oracle GoldenGate, which are separate technologies for data replication and integration​​​​.

The command performs a comprehensive set of database checks prior to a role change (A):TheVALIDATE DATABASEcommand in Data Guard Manager (DGMGRL) is designed to perform an exhaustive check of a specified database's readiness for a role change, such as a switchover or failover.

The command performs network connectivity checks between members of a broker configuration (C):One of the checks includes verifying that the necessary network connectivity exists between the databases in a Data Guard Broker configuration.

The command can be used for a logical standby database (D):TheVALIDATE DATABASEcommand is versatile and can be used for both physical and logical standby databases to ensure their readiness for role changes.

In a Data Guard environment, offloading backups to a physical standby database has certain requirements:

A: Once the primary database is registered in an RMAN catalog, the standby database can also be registered. This allows RMAN to manage backups coherently across both databases and leverage the standby database for backup purposes without interfering with the primary database's workload.

C: Backups of the standby control file taken while connected to the catalog where the database is registered can be used to restore the control file on the primary database. This ensures that backup metadata is consistent across the Data Guard configuration.

Options B and D are incorrect because there is no strict requirement for the order in which the primary and standby databases must be registered in an RMAN catalog. However, it is a common practice to register the primary database first.

When a physical standby database is opened in real-time query mode, which may be referred to as real-time apply when using Active Data Guard, certain operations can disrupt ongoing sessions. However, with features like Application Continuity and the proper configuration of initialization parameters such as STANDBY_DB_PRESERVE_STATES, user sessions and current buffers may be preserved during role transitions such as a switchover or failover. Specifically, the STANDBY_DB_PRESERVE_STATES parameter can be set to preserve none, all, or only user sessions during such transitions. This ensures that in-flight transactions are not lost and that users do not experience disruptions during the role transitions of a physical standby database​​​​.

References

Oracle Data Guard Concepts and Administration​​

Oracle Database Licensing Information User Manual​​

Oracle Data Guard Broker User Manual​

Logical standby databases allow the execution of DDL and DML operations, which makes them suitable for maintaining bitmap indexes and materialized views without affecting the performance of the primary database .

Logical standby databases can be used for performing rolling upgrades and patching with minimum downtime, meeting another requirement .

They also enable the testing of new application software releases against an up-to-date replica of the primary database, fulfilling the last requirement.

Other configurations involving physical standby databases or combinations of logical and physical standby databases might not meet all the specified requirements as efficiently or with the same level of performance isolation for the primary database.

TheRECOVER STANDBY DATABASE FROM SERVICEcommand in RMAN is designed to automate various steps required to recover the standby database, especially when dealing with an archive gap. When this command is executed, the following actions can occur automatically:

Remember all data file names on the standby (1):RMAN has the capability to recall the names and paths of all data files associated with the standby database.

Restart standby in nomount (2):The standby database can be automatically restarted in the NOMOUNT state, allowing recovery operations to proceed without the database being open.

Restore controlfile from primary (3):RMAN can restore the control file from the primary database to the standby system, ensuring that the standby has the most up-to-date control file.

Mount standby database (4):After restoring the control file, the standby database is mounted to prepare for data file recovery.

Rename data files from stored standby names (5):Not typically done automatically by this command.

Restore new data files to new names (6):New data files added to the primary since the last synchronization can be restored to the standby with their correct names.

Recover standby (7):Finally, RMAN will apply any necessary redo logs to bring the standby database up to date with the primary.

While some steps, such as renaming data files (5), typically require manual intervention or scripting, most of the recovery process can be handled by RMAN automatically, streamlining the recovery of the standby database.

The ORA-03172: STANDBY_MAX_DATA_DELAY error indicates that the real-time query on the physical standby database is experiencing delays beyond the specified maximum data delay threshold. Increasing the network bandwidth (Option E) can enhance the speed at which redo data is transferred from the primary to the standby database, thereby reducing the likelihood of exceeding the STANDBY_MAX_DATA_DELAY threshold. Reducing I/O latency on the primary database's storage (Option B) ensures that redo data is generated and shipped more efficiently, further mitigating the risk of delay. These actions, focused on optimizing data transfer and processing speed, address the root causes of the ORA-03172 error in a synchronous Data Guard configuration operating in Maximum Availability mode.

The DBMS_ROLLING package facilitates a rolling upgrade process across a Data Guard configuration. The START PLAN procedure in particular handles several critical actions, including:

Creating a guaranteed restore point on the standby databases (B):This ensures that the standby databases can be reverted to their state before the rolling upgrade process in case of any issues.

Building a LogMiner dictionary on the primary database instance (C):This is necessary for logical standby databases to interpret redo data during the SQL Apply process.

In the context of Oracle Data Guard and Global Database Services (GDS):

DGMGRL may be used to add the Sales configuration to the Prod pool in gds (A):Data Guard Broker's command-line interface DGMGRL can be utilized to manage configurations with GDS, allowing the addition of Data Guard Broker configurations to GDS pools.

Performing a role change with DGMGRL automatically notifies GDS which in turn activates the appropriate services (B):When a role change is executed using DGMGRL, GDS is automatically notified, and it then activates the services that are appropriate for the new database roles.