Applied archive log gap status

Job details

Parameters

Job Summary

• Purpose: The purpose of this job is to monitor and react to gaps and errors in applied archived logs across Oracle database standby instances.
• Why: This job is essential to ensure data consistency and availability in Oracle standby databases by understanding and reacting to delays or issues in log application. Identifying these logs promptly can prevent potential data loss or replication discrepancies, which are critical for disaster recovery and high availability setups.
• Manual checking: You can check for gaps and errors manually in the database by issuing the following SQL commands:

SELECT dest_id, sequence#, status, ERROR from V$ARCHIVE_DEST_STATUS where status != 'ACTIVE';

Implementation Details

• This monitoring task is implemented via a stored procedure named “proc_achive_log_gap_status” that runs on the database server.
• The procedure assesses archived logs from standby databases, checking applied log gaps and reporting errors via dynamic performance views: V$ARCHIVED_LOG and V$ARCHIVE_DEST_STATUS.

Execution and Dependencies

• The job is scheduled to run every 10 minutes by default, ensuring frequent monitoring.
• It depends on itself, as indicated in the job configuration, with a self-cleaning approach on failures to maintain the integrity of subsequent executions.

Parameters and Conditions

• “Ignore destination IDs” to exclude specific destinations if required.
• Conditions for raising alerts are configurable with thresholds for warning and alarm levels based on the size of the log gap.
• Errors identified in V$ARCHIVE_DEST_STATUS can trigger an alarm status, enhancing the immediacy of the response to issues.

Error Handling and Reporting

• The procedure includes robust error handling mechanisms, capturing errors during execution and updating database monitoring tools with appropriate statuses and informational messages.
• Alerts can be configured to notify database administrators or integrated into an automated response system for immediate action.

Report Generation

• The job also supports automated reporting via the dbWatch Report template, presenting key data regarding archived logs, application status, and errors.
• Reports include comprehensive details like destination ID, sequence numbers, and error descriptions, providing a snapshot of the archive log status across multiple destinations.

Importance in Database Administration

• Ensuring that data is correctly and timely replicated in standby systems is critical to maintaining the health and performance of the database environment, particularly in high availability architectures.
• This monitoring job proactively manages data integrity and operational continuity, which is vital for business continuity planning in enterprise setups.

By monitoring applied archive log gaps and statuses across Oracle standby instances, this dbWatch Control Center job plays a crucial role in the risk management and performance optimization of database systems.