25+ Oracle Data Guard Interview Questions [ 95% SUCCESS ] | 2020
Oracle Data Guard Interview Questions and Answers

25+ Oracle Data Guard Interview Questions [ 95% SUCCESS ]

Last updated on 04th Jul 2020, Blog, Interview Questions

About author

Krishnan (Sr Technical Manager )

(5.0) | 16212 Ratings 17956

We provide Oracle Data Guard interview questions and answers to provide students with a valuable opportunity to deepen their understanding of this critical database management tool. Designed to cover a broad spectrum of topics, these questions enhance theoretical knowledge and offer practical insights into real-world scenarios. Students can gain a comprehensive grasp of Oracle Data Guard’s functionalities by delving into scenarios and addressing both basic and advanced concepts. Moreover, including detailed answers helps reinforce understanding and build confidence. Overall, this resource bridges theoretical learning and practical application, offering students a well-rounded preparation for success in their Oracle Data Guard interviews and future roles within the field.


1. What is Oracle Data Guard?

Ans:

Oracle Data Guard is a high-availability and disaster recovery solution provided by Oracle Corporation for Oracle databases. It is designed to ensure the availability, integrity, and reliability of data by maintaining a synchronized copy of a primary database at one or more remote standby databases.

2. Explain the purpose of Oracle Data Guard.

Ans:

The primary purpose of Oracle Data Guard is to provide a reliable and efficient solution for minimizing downtime and data loss in the event of a failure at the primary database site. It helps organizations achieve high availability, disaster recovery, and data protection for their critical Oracle databases.

3. What are the primary components of Oracle Data Guard?

Ans:

  • Primary Database: The main production database that actively serves application requests.
  • Standby Database: A synchronized copy of the primary database that is kept up-to-date to provide failover and data protection.
  • Redo Transport Services: Responsible for transporting redo data from the primary to standby database.
  • Log Apply Services: Apply redo data on standby databases to keep them synchronized with the primary database.
  • Data Guard Broker: A management framework that simplifies the configuration, monitoring, and maintenance of a Data Guard environment.

4. Differentiate between the roles of Primary and Standby databases.

Ans:

The primary database is the main production database actively serving application requests. In contrast, the standby database is a synchronized copy of the primary database kept up-to-date to provide failover and data protection.

Oracle Data Guard Architecture

5. How does Oracle Data Guard provide high availability?

Ans:

Oracle Data Guard achieves high availability through features like fast-start failover, automatic detection of failures, and rapid switchover capabilities. It ensures minimal downtime and data loss during planned or unplanned outages.

6. What is the role of the Data Guard Broker?

Ans:

The Data Guard Broker is a management framework that simplifies the configuration, monitoring, and maintenance of a Data Guard environment. It automates tasks such as role transitions, switchover, and failover, providing a centralized interface for managing the Data Guard setup.

7. Describe the various Data Guard protection modes.

Ans:

  • Maximum Protection: Synchronous redo transport and synchronous apply on standby.
  • Maximum Availability: Synchronous redo transport with asynchronous apply on standby.
  • Maximum Performance: Asynchronous redo transport and asynchronous apply on standby.

8. Explain the difference between synchronous and asynchronous Data Guard modes.

Ans:

 
Synchronous Data Guard
Asynchronous Data Guard
Real-time data transfer Delayed data transfer
Requires acknowledgment from the standby before committing Does not wait for acknowledgment before committing
Higher performance impact on the primary database Lower performance impact on the primary database
More dependent on network quality Less dependent on network quality
Provides higher data protection Provides lower data protection
Lower latency Higher latency

9. How do you configure Oracle Data Guard using the Data Guard Broker?

Ans:

The Data Guard Broker is configured through the Oracle Enterprise Manager or command-line interface (DGMGRL). It simplifies the setup and management of Data Guard configurations, automating many tasks involved in maintaining standby databases.

10. What is a Redo Transport Service in Oracle Data Guard?

Ans:

The Redo Transport Service is responsible for transmitting redo data from the primary database to the standby database. It ensures that changes made to the primary database are replicated to the standby database, keeping them synchronised. The two modes of redo transport are synchronous and asynchronous.

11. How is log transport initiated from the Primary to Standby database?

Ans:

Log transport from the Primary to Standby database is initiated through Oracle Data Guard by using the log shipping mechanism. Redo log files generated on the Primary database are shipped to the Standby database either synchronously or asynchronously, depending on the configuration.

12. Explain the concept of the Far Sync instance in Oracle Data Guard.

Ans:

A Far Sync instance in Oracle Data Guard serves as a remote redo transport destination that acts as a relay between the Primary and Standby databases. It allows for zero data loss configurations without the need for a physical standby at the remote site.

13. How does Oracle Data Guard handle network failures between the Primary and Standby databases?

Ans:

Oracle Data Guard handles network failures by utilizing features like Fast-Start Failover and automatic detection of network issues. Fast-Start Failover can automatically fail over to a standby database in case of a communication failure, ensuring minimal downtime.

14. Enumerate the advantages associated with the maximum protection mode.

Ans:

The advantages of Maximum Protection mode in Oracle Data Guard include:

  • Zero data loss in case of a primary database failure.
  • Synchronous redo transport to ensure that transactions are committed on the standby before being acknowledged on the primary.
  • Highest level of data protection at the cost of potential performance impact.

15. Provide an overview of the requisite services on the standby database.

Ans:

Standby databases in Oracle Data Guard require services such as Redo Apply, Managed Recovery, and Active Data Guard. Redo Apply is responsible for applying redo data to keep the standby synchronized, Managed Recovery manages the recovery process, and Active Data Guard enables read-only access to the standby for reporting purposes.

16. What are the types of Standby databases in Oracle Data Guard?

Ans:

  • Physical Standby: Maintains an identical copy of the primary database.
  • Logical Standby: Converts redo data into SQL and applies it to the standby database.
  • Snapshot Standby: Acts as a physical standby but can be temporarily converted to a fully updatable database for testing purposes.

17. How do you switch roles between the Primary and Standby databases?

Ans:

Role switching is achieved using the Data Guard broker or manually with SQL commands. The ALTER DATABASE statement with the SET STANDBY TO [PRIMARY/LOGICAL/PHYSICAL] clause is used to switch roles.

18. Explain the significance of the Data Guard Observer.

Ans:

The Data Guard Observer is a background process that monitors the primary and standby databases. It facilitates automatic failover and fast-start failover decisions by continuously monitoring the health of the databases and network connectivity.

19. What is the purpose of the LOG_ARCHIVE_DEST_ n parameters in Data Guard configuration?

Ans:

  • These parameters define the destinations for archived redo log files.
  • In a Data Guard configuration, they specify where the redo logs should be archived and sent to ensure data consistency between the primary and standby databases.

20. Identify the three primary services provided by Data Guard software.

Ans:

The three primary services provided by Data Guard software are:

  • Redo Transport: Manages the shipping of redo data from the primary to the standby.
  • Log Apply: Applies redo data on the standby database to keep it synchronized.
  • Data Guard Broker: Provides a framework for the management and monitoring of Data Guard configurations.

    Subscribe For Free Demo

    [custom_views_post_title]

    21. Specify the three available protection modes in the software.

    Ans:

    • Maximum Protection: This mode ensures that no data loss will occur in the event of a primary database failure. Transactions are not committed on the primary until they are acknowledged by at least one synchronous standby database.
    • Maximum Availability: In this mode, transactions are committed on the primary as soon as they are committed locally. However, the system waits for acknowledgement from at least one standby database, ensuring minimal data loss in the event of a primary database failure.
    • Maximum Performance: This mode allows transactions to be committed on the primary without waiting for any acknowledgment from the standby databases. This provides the highest performance but may result in potential data loss in the event of a primary database failure.

    22. How can you monitor the lag between the Primary and Standby databases?

    Ans:

    You can monitor the lag between the Primary and Standby databases by querying the V$DATAGUARD_STATS view on the primary database. The TRANSPORT LAG column in this view provides information about the delay in applying redo data on the standby database.

    • SELECT MAX(VALUE) AS “TRANSPORT LAG”
    • FROM V$DATAGUARD_STATS
    • WHERE NAME = ‘transport lag’;

    23. What is the difference between physical and logical standby databases?

    Ans:

    Physical Standby Database:

    It maintains an identical copy of the primary database’s physical structure, including data files, tablespaces, and redo logs. Redo data from the primary is continuously applied to the standby, making it an exact replica.

    Logical Standby Database:

    It maintains a logical representation of the primary database, converting redo data into SQL statements. This allows for different database structures on the standby, making it suitable for activities like reporting or data transformation.

    24. How do you perform a switchover operation in Oracle Data Guard?

    Ans:

    To perform a switchover operation in Oracle Data Guard, use the following steps:

    Connect to the primary database:

      CONNECT SYS AS SYSDBA;

    Issue the switchover command:

      ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY;

    Connect to the new primary (formerly standby) database:

      ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH;

    25. How do you troubleshoot gaps in redo log transmission in Data Guard?

    Ans:

    • Check the Data Guard broker logs for any error messages.
    • Query the DBA_LOGSTDBY_EVENTS view on the standby database to identify gaps.
    • Ensure that the network between the primary and standby databases is stable.
    • Verify the availability of archived redo logs on the primary database.
    • Use the ADRCI utility to check for any relevant trace files or alert logs.

    26. Explain the concept of Data Guard Fast-Start Failover.

    Ans:

    Data Guard Fast-Start Failover: It is a feature that automates the failover process in Oracle Data Guard. It enables the automatic promotion of a standby database to the primary role in the event of a failure without manual intervention. Fast-Start Failover relies on a Fast-Start Failover observer, which monitors the health of the primary and standby databases and initiates the failover if necessary.

    27. How do you perform a failover operation in Oracle Data Guard?

    Ans:

      CONNECT SYS AS SYSDBA;

    Issue the failover command:

      ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY WITH SESSION SHUTDOWN;

    28. What is the role of the Flashback Database feature in Oracle Data Guard?

    Ans:

    Flashback Database: It is a feature that enables you to revert a database to a previous point in time by using the archived redo logs. In Oracle Data Guard, Flashback Database can be used to quickly recover a standby database to a specific SCN (System Change Number) without having to perform a complete restore from a backup, reducing downtime in case of logical errors.

    29. How can you configure the Data Guard Observer for automatic failover?

    Ans:

    • Set up and configure the Data Guard Broker on the primary and standby databases.
    • Start the Data Guard Observer on a separate machine.
    • Register the observer with the Data Guard configuration.
    • Configure the observer to monitor the primary and standby databases.
    • Set the FastStartFailoverThreshold parameter to specify the conditions for automatic failover.
    • Monitor the observer logs for any alerts or notifications related to failover events.

    30. Explain the use of the Data Guard CLI (Command-Line Interface).

    Ans:

    The Data Guard Command-Line Interface (DGMGRL) is a utility in Oracle that allows database administrators to manage and monitor Data Guard configurations from the command line. It provides a set of commands for configuring, monitoring, and maintaining Data Guard configurations. DBAs can use DGMGRL to perform tasks such as switchover, failover, and monitoring the status of the primary and standby databases.

    31. What is the role of the Data Guard Monitor in Oracle Enterprise Manager (OEM)?

    Ans:

    The Data Guard Monitor in Oracle Enterprise Manager (OEM) is a graphical interface that enables database administrators to monitor and manage Data Guard configurations. DBAs can use OEM to perform various Data Guard operations, such as configuring, testing, and troubleshooting, through a user-friendly web-based interface.

    32. How do you handle switchover and failover in a RAC (Real Application Clusters) environment with Data Guard?

    Ans:

    In a Real Application Clusters (RAC) environment with Data Guard, switchover and failover operations involve additional considerations. Switchover can be performed at the RAC primary database level by switching the primary role to a different RAC instance. Failover, on the other hand, involves promoting a standby database to the primary role in case of a failure. 

    33. Discuss the impact of redo transport compression in Oracle Data Guard.

    Ans:

    Redo transport compression in Oracle Data Guard helps reduce the amount of network bandwidth required for transmitting redo data between the primary and standby databases. By compressing redo data before transmission, it minimizes the network overhead, improving overall performance and reducing data transfer times. However, it’s important to note that redo transport compression may introduce additional CPU overhead on both the primary and standby databases due to the compression and decompression processes.

    34. Describe the process of adding a new Standby database to an existing Data Guard configuration.

    Ans:

    • Take a consistent backup of the primary database.
    • Copy the backup to the server hosting the new standby database.
    • Restore the backup on the new standby database.
    • Configure the necessary parameters in the initialization parameter file.
    • Start the new standby database in standby mode.
    • Register the new standby database with the Data Guard configuration on the primary database.

    35. What is the importance of the Data Guard Transport Services in the configuration?

    Ans:

    Data Guard Transport Services are crucial components that facilitate the reliable and efficient transfer of redo data between the primary and standby databases. The services include Redo Transport, which manages the transmission of redo data, and the Net Services, responsible for the network communication between primary and standby databases. Proper configuration of these services ensures data integrity, low latency, and high availability in the Data Guard environment.

    36. Explain the different network considerations for Data Guard configuration.

    Ans:

    Network considerations in Data Guard configuration are critical for optimal performance and reliability. These include bandwidth requirements, network latency, and network security. A reliable and high-bandwidth network connection is essential to transmit redo data efficiently between the primary and standby databases. Low latency helps minimize the time lag between changes on the primary and their application on the standby. Additionally, ensuring secure communication over the network is crucial to protect sensitive data during transmission.

    37. What are the prerequisites for setting up Oracle Active Data Guard?

    Ans:

    • Setting up Oracle Active Data Guard requires several prerequisites:
    • Oracle Database Enterprise Edition with the Oracle Active Data Guard option.
    • A working Oracle Data Guard configuration with a primary and standby database.
    • Appropriate licensing for Oracle Active Data Guard.
    • Configured and synchronized Oracle Grid Infrastructure (if using Oracle RAC).
    • Properly configured redo transport services for real-time redo apply on the standby.

    38. How does Oracle Data Guard handle tablespace additions or modifications on the Primary database?

    Ans:

    • Oracle Data Guard handles tablespace additions or modifications on the primary database through redo log shipping.
    • Any changes to the database, including tablespace additions or modifications, generate redo log entries.
    • These redo entries are transmitted to the standby database, where the changes are applied to maintain synchronization.

    39. How does Oracle Data Guard handle temporary tablespaces and global temporary tables?

    Ans:

    Oracle Data Guard handles temporary tablespaces and global temporary tables by replicating the necessary metadata and ensuring consistency between the primary and standby databases. Temporary tablespaces, used for sorting and joining operations, are part of the redo log data transmitted to the standby. Global temporary tables, which store temporary data, are also replicated to maintain data consistency.

    40. What is the role of the Data Guard SQL Apply process?

    Ans:

    The Data Guard SQL Apply process is responsible for applying SQL changes from the redo logs to the standby database. It operates at the SQL level, interpreting and executing SQL statements received from the primary database’s redo logs. This process is essential for maintaining logical consistency between the primary and standby databases.

    41. How can you monitor the performance of Oracle Data Guard?

    Ans:

    Oracle Data Guard performance can be monitored using various tools and techniques. Oracle Enterprise Manager (OEM) provides a comprehensive interface for monitoring Data Guard configurations. Key performance indicators such as redo apply rate, transport lag, and synchronization status can be monitored through OEM’s Data Guard Dashboard. 

    42. Discuss the impact of different database character sets on Data Guard configuration.

    Ans:

    • Different database character sets may impact Data Guard due to potential issues with data conversion during replication.
    • It’s crucial to ensure that the primary and standby databases have compatible character sets to avoid data corruption or loss.
    • Using the Oracle Database Character Set Scanner can help identify potential issues.
    • In case of character set incompatibility, conversion can be achieved using the Database Migration Assistant for Unicode (DMU) or other appropriate methods.

    43. What is the purpose of the Data Guard Broker DGMGRL utility?

    Ans:

    The Data Guard Broker DGMGRL utility is a command-line interface for managing and monitoring Oracle Data Guard configurations. It provides a centralized control point for configuring, monitoring, and controlling Data Guard configurations. DGMGRL simplifies tasks such as switchover, failover, and configuration changes. It allows for scripting and automation of routine Data Guard operations, making it an essential tool for database administrators managing Data Guard environments.

    44. How do you perform rolling database upgrades in Oracle Data Guard?

    Ans:

    Rolling database upgrades in Oracle Data Guard involve upgrading one database at a time while maintaining the overall system’s availability. The process typically includes performing a switchover to a standby database, upgrading the former primary (now standby) database, and then switching back.

    45. Explain the concept of Snapshot Standby databases.

    Ans:

    A Snapshot Standby database in Oracle Data Guard allows temporary conversion of a physical standby database into a read-write, fully updatable state. This enables running reports, testing, or other non-production activities without affecting the primary database. After completing the desired tasks, the Snapshot Standby can be easily converted back to a physical standby database.

    46. What are the considerations for Data Guard switchover in a Maximum Availability configuration?

    Ans:

    • In a Maximum Availability configuration, considerations for Data Guard switchover include ensuring minimal downtime and data loss.
    • Before initiating a switchover, verify that the standby database is in sync with the primary.
    • Implement Fast-Start Failover to automate switchover in case of a failure.
    • It’s crucial to have a well-defined switchover plan, conduct thorough testing in a controlled environment, and communicate the planned switchover to relevant stakeholders to minimize any potential impact.

    47. How does Oracle Data Guard support multi-tenancy in Oracle Database 12c and later versions?

    Ans:

    Oracle Data Guard supports multi-tenancy in Oracle Database 12c and later versions by allowing the configuration of pluggable databases (PDBs) as part of a Data Guard configuration. Each PDB within a container database (CDB) can be treated as an individual entity in a Data Guard setup. 

    48. What is the importance of the LOG_ARCHIVE_DEST_STATE_n parameter?

    Ans:

    • The LOG_ARCHIVE_DEST_STATE_n parameter is used to control the state (ENABLE or DEFER) of individual log archive destinations in Oracle Data Guard configurations.
    • This parameter allows dynamic changes to the configuration, enabling administrators to activate or deactivate specific destinations without modifying the entire configuration.
    • This flexibility is valuable for scenarios where certain standby databases need to be temporarily taken offline or brought online based on operational requirements.

    49. How can you automate the failback process after a failover in Oracle Data Guard?

    Ans:

    Automating the failback process after a failover in Oracle Data Guard involves scripting and leveraging the DGMGRL utility. By creating a failback script, administrators can automate the steps required to reinstate the original primary database after a failover. This includes tasks such as reconfiguring the Data Guard setup, initiating a switchover, and validating the configuration. Automating failback reduces downtime and ensures a more efficient recovery process.

    50. What are the considerations for configuring Data Guard in an Oracle Multitenant Container Database (CDB) environment?

    Ans:

    • Ensure that both the container database (CDB) and pluggable databases (PDBs) are included in the Data Guard configuration.
    • Plan for the synchronization of PDBs across the primary and standby databases.
    • Understand how Oracle Data Guard interacts with the Container Database’s architecture, especially when dealing with PDBs in different states (e.g., open, closed).
    • Test and validate the entire Data Guard setup, including failover and switchover operations, to ensure seamless operations in a multi-tenant environment.
    Course Curriculum

    Best Oracle Data Guard Certification Course with Advanced Concepts from Real Time Experts

    Weekday / Weekend BatchesSee Batch Details

    51. How do you handle the Oracle Data Guard configuration with a pluggable database (PDB)?

    Ans:

    To configure Oracle Data Guard with a pluggable database (PDB), you need to ensure that the primary and standby databases have the same PDBs and corresponding data files. The Data Guard configuration is set up at the container database (CDB) level. You can create a pluggable database on the primary, and the Data Guard configuration replicates the PDB changes to the standby.

    52. Explain the impact of Oracle Data Guard on performance tuning strategies.

    Ans:

    Oracle Data Guard introduces additional considerations for performance tuning. While the standby database is typically in read-only mode, the primary database may experience performance overhead due to the overhead of redo transport and applying redo data on the standby. Efficient network configuration and proper sizing of the redo transport and apply processes are crucial for maintaining optimal performance.

    53. What is the significance of the Data Guard Observer Fast Application Notification (FAN)?

    Ans:

    The Fast Application Notification (FAN) feature of the Data Guard Observer helps in providing real-time updates about database role changes (such as switchover or failover) to applications. This enables applications to dynamically adjust their behavior based on the database role, improving high availability and reducing downtime.

    54. How do you perform rolling upgrades of Oracle Grid Infrastructure in a Data Guard environment?

    Ans:

    Rolling upgrades in an Oracle Grid Infrastructure with Data Guard involve upgrading one node at a time. The Data Guard configuration allows the standby databases to continue serving while the primary undergoes the upgrade. After upgrading the primary and standby databases on one node, you can proceed to the next node, ensuring a smooth transition with minimal downtime.

    55. How does Oracle Data Guard handle switchover operations in a Physical Standby configuration?

    Ans:

    • In a Physical Standby configuration, a switchover operation involves changing the roles of the primary and standby databases.
    • The primary database becomes the standby, and the standby becomes the new primary.
    • Data Guard ensures that all changes from the original primary are applied to the new primary before the switchover is complete, minimizing data loss and ensuring consistency.

    56. Explain the concept of the Observer-only mode in Data Guard.

    Ans:

    The Observer-only mode in Data Guard allows the Data Guard Observer to monitor and coordinate role changes without actively participating in the decision-making process. While in this mode, the Observer provides notifications to applications about database role changes (FAN events) but doesn’t influence the automatic or manual switchover or failover decisions.

    57. What are the considerations for Data Guard configuration with different Oracle Database editions?

    Ans:

    Data Guard features vary between Oracle Database editions. Enterprise Edition provides advanced features like real-time apply, rolling upgrades, and Active Data Guard. Standard Edition supports basic Data Guard configurations but lacks certain high-end features. Consider the edition limitations while planning your Data Guard architecture.

    58. Discuss the impact of changing the primary key on tables in a Data Guard environment.

    Ans:

    Changing the primary key on tables in a Data Guard environment involves redo generation. This redo needs to be transported to the standby and applied. Depending on the size of the table and the frequency of changes, this can impact network utilization and standby database performance. It’s crucial to monitor and plan for potential downtime during such operations.

    59. How do you handle the addition of a new tablespace on the Primary database in Oracle Data Guard?

    Ans:

    When adding a new tablespace on the primary, Data Guard ensures the changes are replicated to the standby. Ensure that the standby has sufficient space, and the addition of the tablespace doesn’t adversely affect the redo transport and apply processes. Monitor the Data Guard logs for any issues during the addition of tablespaces.

    60. What is the purpose of the ‘VALID_FOR’ parameter in the LOG_ARCHIVE_DEST_n parameter?

    Ans:

    The ‘VALID_FOR’ parameter in the LOG_ARCHIVE_DEST_n parameter specifies the conditions under which a standby database can be considered valid for switchover or failover. It allows you to define criteria such as role, delay threshold, or real-time apply to determine the readiness of a standby database for role changes in the Data Guard configuration.

    61. Explain the role of the Data Guard transport services in handling network outages.

    Ans:

    • The Data Guard transport services, including Redo Transport Services and Data Transport Services, play a crucial role in ensuring data consistency between the primary and standby databases.
    • During network outages, Redo Transport Services hold redo data in standby redo log files on the primary database until the network is restored, preventing data loss.
    • Data Transport Services handle the transfer of archived redo logs to maintain synchronization between the primary and standby databases.

    62. How does Oracle Data Guard support cross-platform database migrations?

    Ans:

    Oracle Data Guard supports cross-platform database migrations through the “Transitional Data Guard” feature. This involves creating a standby database on the target platform while the primary database is still running. Once the standby is in sync, a switchover is performed, making the new platform the primary. This method minimizes downtime during the migration process.

    63. Discuss the significance of the Data Guard Fast-Start Parallel Redo Apply feature.

    Ans:

    • The Fast-Start Parallel Redo Apply feature in Oracle Data Guard enhances the efficiency of redo apply operations on standby databases.
    • It enables parallel processing of redo data, utilizing multiple CPU cores to apply changes concurrently.
    • This feature significantly improves the performance of redo apply operations, reducing the time needed to apply redo logs on the standby and keeping it synchronized with the primary database.

    64. What precautions should be taken before performing a switchover in Oracle Data Guard?

    Ans:

    All standby databases are in sync with the primary. There are no unresolved issues, such as gaps in redo logs. Sufficient network bandwidth is available for the switchover operation. Applications are quiesced to prevent new transactions on the primary during the switchover.

    65. Explain the steps involved in converting a Physical Standby database to a Snapshot Standby.

    Ans:

    • Ensure the physical standby is in sync with the primary.
    • Convert the physical standby to a logical standby.
    • Open the logical standby database in snapshot standby mode.
    • Perform testing and reporting activities on the snapshot standby.

    66. How can you monitor and troubleshoot redo transport lag in Oracle Data Guard?

    Ans:

    Redo transport lag in Oracle Data Guard can be monitored and troubleshooted using the V$DATAGUARD_STATS view. Specifically, the TRANSPORT_LAG column provides information about the lag between the primary and standby databases. Additionally, the SHOW and REPORT commands in the Data Guard broker interface offer insights into transport lag and can help identify and address network or configuration issues causing the lag.

    67. Discuss the impact of changing the database character set on Data Guard configuration.

    Ans:

    Changing the database character set in Oracle Data Guard can have a significant impact, as it requires careful consideration. The primary and standby databases must have the same character set for proper replication. Changing the character set involves downtime, and it is essential to follow Oracle’s guidelines for character set conversion.

    68. What is the role of the ‘MAX_CONNECTIONS’ parameter in the Data Guard configuration?

    Ans:

    The ‘MAX_CONNECTIONS’ parameter in the Data Guard configuration specifies the maximum number of network connections that can be established between the primary and standby databases for redo transport. It helps control the resource usage and prevents excessive network connections, optimizing the performance of redo transport services. 

    69. How does Oracle Data Guard handle changes to the UNDO tablespace on the Primary database?

    Ans:

    • Oracle Data Guard automatically replicates changes to the UNDO tablespace from the primary database to standby databases as part of redo data.
    • UNDO changes are crucial for maintaining data consistency. 
    • When a transaction is committed on the primary, the associated UNDO changes are captured in redo logs and transmitted to standby databases.

    70. Explain the process of adding a new column to a table in a Data Guard environment.

    Ans:

    • Make the structural change (add the column) on the primary database.
    • Allow sufficient time for the change to be captured in redo logs and transmitted to standby databases.
    • Verify that the structural change is applied on the standby databases by monitoring the redo apply progress.
    • Ensure that any dependent applications or queries are modified to accommodate the new column.
    Course Curriculum

    Enroll in Oracle Data Guard Training with Advanced Concepts

    • Instructor-led Sessions
    • Real-life Case Studies
    • Assignments
    Explore Curriculum

    71. What considerations should be taken into account when integrating Oracle GoldenGate with Data Guard?

    Ans:

    • When integrating Oracle GoldenGate with Data Guard, consider the following:
    • Ensure the Oracle GoldenGate version is compatible with both the Oracle Database and Data Guard versions.
    • Configure GoldenGate Extract and Replicat processes to capture and apply changes consistently across primary and standby databases.
    • Synchronize the trail files’ location between the primary and standby sites.
    • Coordinate the start and stop of Oracle GoldenGate processes with Data Guard operations to maintain consistency during switchover or failover.

    72. How do you configure and manage the Data Guard Observer in a Real Application Clusters (RAC) environment?

    Ans:

    • Configure the Data Guard broker with observer support using DGMGRL.
    • Set up the Observer on a separate host to avoid a single point of failure.
    • Configure the observer using the DGMGRL command-line interface or Oracle Enterprise Manager.
    • Monitor the observer’s status and performance using the SHOW OBSERVER command in DGMGRL.
    • Consider using static connect identifiers to ensure proper failover and observer communication in a RAC environment.

    73. Discuss the steps for implementing Oracle Active Data Guard with read-only standby databases.

    Ans:

    • Enable Real-Time Query on the primary and standby databases.
    • Configure the Data Guard broker to enable fast-start failover.
    • Set the standby databases to the read-only mode to allow reporting queries.
    • Utilize the DBMS_ROLLING package to perform rolling database upgrades with minimal downtime.
    • Monitor and manage the environment to ensure the read-only standby databases stay in sync with the primary for reporting purposes.

    74. What is the purpose of the ‘LOG_ARCHIVE_FORMAT’ parameter in Data Guard configuration?

    Ans:

    The ‘LOG_ARCHIVE_FORMAT’ parameter in Data Guard configuration specifies the format of the archived redo log filenames. It plays a crucial role in ensuring consistent naming conventions between the primary and standby databases. A uniform filename format is necessary for Oracle Data Guard to properly identify and apply archived redo logs on standby databases, maintaining synchronization with the primary.

    75. Explain the impact of database rolling patches on Oracle Data Guard.

    Ans:

    • Ensuring compatibility of patches with both primary and standby databases.
    • Applying patches in a rolling fashion to minimize downtime.
    • Monitoring redo apply progress during the patching process to maintain synchronization.
    • Coordinating with the Data Guard broker to automate and streamline the rolling patch process.

    76. How can you automate the failover process in Oracle Data Guard using the DGMGRL command-line interface?

    Ans:

    • Configure the Data Guard broker with the necessary parameters and settings.
    • Use the DGMGRL command-line interface to connect to the broker.
    • Issue the FAILOVER command to initiate an automated failover.
    • Monitor the failover process using DGMGRL and verify the new primary database’s status.

    77. Discuss the role of the ‘ARCHIVE_LAG_TARGET’ parameter in managing redo transport lag.

    Ans:

    The ‘ARCHIVE_LAG_TARGET’ parameter in Oracle Data Guard configuration specifies the desired maximum acceptable lag between the primary and standby databases in terms of archived redo log files. Setting this parameter helps manage redo transport lag by instructing the system to automatically adjust the rate of shipping redo logs to meet the specified target. This parameter is useful for controlling the acceptable delay and maintaining a balance between performance and data protection.

    78. What is the significance of the ‘Apply Instance Reconnect’ feature in Oracle Data Guard?

    Ans:

    The ‘Apply Instance Reconnect’ feature in Oracle Data Guard allows a standby database’s apply instance to automatically reconnect to the primary database after a network outage or disruption. This feature ensures the continuous application of redo logs even if there are temporary interruptions in the network connectivity between the primary and standby databases, enhancing the overall resilience of the Data Guard configuration.

    79. How does Oracle Data Guard handle changes to the database time zone on the Primary database?

    Ans:

    Oracle Data Guard automatically replicates changes to the database time zone from the primary database to standby databases through redo logs. When the time zone is altered on the primary, the associated changes are captured in redo logs and transmitted to standby databases during normal replication.

    80. Explain the considerations for integrating Oracle Data Guard with Oracle Streams.

    Ans:

    • When integrating Oracle Data Guard with Oracle Streams, considerations include:
    • Ensuring compatibility between the versions of Data Guard and Oracle Streams components.
    • Monitoring and troubleshooting the integrated environment to maintain data consistency and minimize replication lag.
    • Implementing proper failover and switchover procedures to handle changes in the primary or standby roles in the integrated setup.
    Oracle Data Guard Sample Resumes! Download & Edit, Get Noticed by Top Employers! Download

    81. What is the purpose of the ‘DELAY’ parameter in the LOG_ARCHIVE_DEST_ n configuration?

    Ans:

    The ‘DELAY’ parameter in the LOG_ARCHIVE_DEST_ n configuration specifies the time delay, in minutes, before archived redo logs are sent from the primary database to the specified destination. This parameter helps introduce a time lag in applying changes at the standby, which can be useful for various purposes, such as avoiding the immediate application of potentially erroneous transactions or providing a time window for recovery before applying logs at the standby.

    82. Discuss the impact of the ‘ENABLE_FAST_START_FAILOVER’ parameter on Data Guard behavior.

    Ans:

    The ‘ENABLE_FAST_START_FAILOVER’ parameter in Data Guard configuration enables or disables the Fast-Start Failover feature. When enabled, it allows for automatic and rapid failover to a standby database in case of a failure on the primary. This parameter impacts Data Guard behavior by providing a mechanism for minimizing downtime and ensuring high availability.

    83. How do you monitor and resolve network congestion issues in Oracle Data Guard?

    Ans:

    • Use tools like DGMGRL and Data Guard broker logs to monitor redo transport and apply status.
    • Check the V$ARCHIVE_DEST and V$DATAGUARD_STATS views for information on network and redo transport lag.
    • Adjust the ‘ARCHIVE_LAG_TARGET’ parameter to control the acceptable redo transport lag.
    • Optimize network bandwidth, and consider using Oracle Advanced Compression to reduce the volume of transmitted redo data.

    84. Explain the use of the ‘DB_UNIQUE_NAME’ parameter in Data Guard configuration.

    Ans:

    The ‘DB_UNIQUE_NAME’ parameter in Data Guard configuration specifies a unique identifier for each database within a Data Guard configuration. It helps differentiate between primary and standby databases, ensuring proper identification during failover, switchover, and other Data Guard operations. Each database in the configuration must have a distinct ‘DB_UNIQUE_NAME’ to prevent conflicts and facilitate the correct routing of redo data between the primary and standby databases.

    85. Discuss the steps for transitioning from a Physical Standby to a Logical Standby database.

    Ans:

    Stop redo apply on the physical standby:

      ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

    Convert the physical standby to a snapshot standby:

      ALTER DATABASE CONVERT TO SNAPSHOT STANDBY;

    Open the database in snapshot standby mode:

      ALTER DATABASE OPEN;

    Start redo apply on the logical standby:

      ALTER DATABASE START LOGICAL STANDBY APPLY;

    86. How does Oracle Data Guard handle rolling upgrades of the Oracle Database software?

    Ans:

    Oracle Data Guard supports rolling upgrades of the Oracle Database software by allowing one database at a time to be upgraded while the others remain operational. The process involves:

    • Upgrading the standby databases first.
    • Performing a role transition to make the upgraded standby the primary.
    • Upgrading the original primary (now a standby) while the new primary is operational.
    • Completing the upgrade process with a switchover or failover as needed.

    87. What is the role of the ‘MAX_FAILURE’ parameter in Data Guard Fast-Start Failover configuration?

    Ans:

    The ‘MAX_FAILURE’ parameter in Data Guard Fast-Start Failover configuration specifies the maximum number of consecutive failures allowed before initiating a fast-start failover. If the number of consecutive failures exceeds the specified value, Data Guard automatically triggers a failover to a standby database. This parameter helps prevent unnecessary failovers in case of transient issues while ensuring swift failover in the event of sustained problems with the primary database.

    88. Explain the impact of changing the database block size on Data Guard configuration.

    Ans:

    Changing the database block size in Oracle Data Guard can have a significant impact and requires careful consideration. Both the primary and standby databases must have the same block size for proper replication. Changing the block size involves downtime, as it necessitates rebuilding the standby database to match the new block size.

    89. Discuss the considerations for integrating Oracle Data Guard with Oracle Cloud.

    Ans:

    • Ensuring that the Oracle Database versions on-premises and in the cloud are compatible.
    • Establishing secure and reliable network connectivity between on-premises and cloud environments.
    • Adhering to Oracle Cloud best practices and recommendations for high availability, security, and performance.
    • Utilizing Oracle Cloud features such as Oracle Cloud Infrastructure (OCI) and Autonomous Database for optimized Data Guard configurations in the cloud.

    90. How does the ‘SYNC’ mode differ from the ‘ASYNC’ mode in Data Guard configuration?

    Ans:

    SYNC Mode:

    In this mode, transactions are considered committed on the primary only after they are transmitted and acknowledged by at least one synchronous standby. This ensures a high level of data protection but may introduce latency and performance overhead due to waiting for acknowledgments.

    ASYNC Mode:

    In this mode, transactions are committed on the primary without waiting for acknowledgment from the standby databases. While this minimizes performance impact, it may introduce a potential for data loss in the event of a primary database failure before changes reach the standby.

    91. Explain the process of adding a new data file to a tablespace in Oracle Data Guard.

    Ans:

    • Add the data file to the primary database using the ALTER TABLESPACE statement.
    • Allow time for the addition of the data file to be captured in redo logs and transmitted to standby databases.
    • Monitor the redo apply progress on standby databases to ensure the new data file is applied.
    • Optionally, manually add the data file to each standby database if needed, using the same ALTER TABLESPACE statement.
    • Verify the synchronization and consistency of the tablespaces across the primary and standby databases.

    92. What is the role of the ‘LOG_ARCHIVE_DUPLEX_DEST’ parameter in Data Guard configuration?

    Ans:

    The ‘LOG_ARCHIVE_DUPLEX_DEST’ parameter in Data Guard configuration specifies a secondary destination for archived redo logs. It is used to duplicate archived redo logs to an additional location, providing an extra level of redundancy. This parameter is often set with ‘LOG_ARCHIVE_DEST_2’ to configure a secondary destination for archived redo logs.

    93. Discuss the steps involved in transitioning from a Physical Standby to a Snapshot Standby.

    Ans:

    • Ensure the physical standby is in sync with the primary.
    • Convert the physical standby to a snapshot standby using the ALTER DATABASE CONVERT TO SNAPSHOT STANDBY statement.
    • Open the snapshot standby in read-write mode to allow testing and reporting activities.
    • Perform necessary testing and reporting on the snapshot standby.
    • If needed, convert the snapshot standby back to a physical standby using the ALTER DATABASE CONVERT TO PHYSICAL STANDBY statement.

    94. How can you use the Data Guard Broker to configure and manage multiple standby databases?

    Ans:

    • Configure Data Guard broker settings using DGMGRL or Oracle Enterprise Manager (OEM).
    • Create a broker configuration with primary and multiple standby databases.
    • Define and set properties for each database in the configuration.
    • Use the broker to monitor the status of the databases, redo transport, and apply services.
    • Perform switchover and failover operations through the broker for seamless management of multiple standby databases.

    95. What is the significance of the ‘REOPEN’ clause in the Data Guard Broker configuration?

    Ans:

    The ‘REOPEN’ clause in the Data Guard Broker configuration is used to reopen a database that was previously closed. This is particularly relevant when there are changes in the configuration, such as adding or removing databases, and the affected databases need to be reopened to apply the new configuration settings. The ‘REOPEN’ clause allows for a controlled and synchronized reopening of databases within the Data Guard configuration.

    96. How do you monitor redo transport services using Oracle Enterprise Manager (OEM)?

    Ans:

    • Log in to OEM and navigate to the Data Guard section.
    • Use the Data Guard overview page to view the status of the primary and standby databases.
    • Access the Data Guard performance pages to monitor redo transport lag, apply lag, and other relevant metrics.
    • Set up notifications or alerts in OEM to receive notifications about any issues with redo transport or apply services.
    • Utilize the graphical interface provided by OEM to visually track the performance and health of redo transport services over time.

    97. Discuss the considerations for integrating Oracle Data Guard with Oracle Exadata.

    Ans:

    Integrating Oracle Data Guard with Oracle Exadata involves several key considerations. First, performance optimization is crucial, and the network bandwidth between primary and standby sites should be sufficient. Additionally, networking and connectivity must be robust, leveraging features like InfiniBand for optimized data transfer.

    98. Explain the impact of changing the database compatibility parameter on Data Guard behavior.

    Ans:

    Changing the database compatibility parameter in Oracle can significantly impact Data Guard behavior, especially during rolling upgrades. It’s important to ensure that the new compatibility level is supported by all databases in the Data Guard configuration. This change may necessitate re-creating the standby database to match the new compatibility level. The process involves breaking the Data Guard configuration, changing the compatibility, and then re-establishing the configuration.

    99. What is the role of the ‘STANDBY_MAX_DELAY’ parameter in Oracle Data Guard?

    Ans:

    The ‘STANDBY_MAX_DELAY’ parameter plays a critical role in Oracle Data Guard by specifying the maximum allowable time delay for Redo Apply on a physical standby database. It helps manage the lag between the primary and standby databases. If the Redo Apply on the standby cannot keep up within the specified delay, the standby database may be automatically disabled to prevent data divergence. 

    100. How does Oracle Data Guard handle changes to the database character set on the Primary database?

    Ans:

    • Handling changes to the database character set on the primary database in an Oracle Data Guard configuration is a complex process.
    • Data Guard supports character set conversion during a rolling upgrade, but changing the character set directly may require additional steps.
    • Before making such changes, it’s crucial to ensure that the new character set is supported by both the primary and standby databases.
    • The process may involve creating a new standby database with the desired character set, switching over to the new standby, and then recreating the original standby with the new character set.


    Are you looking training with Right Jobs?

    Contact Us
    Get Training Quote for Free