Dataguard archivelog apply gap
Job details
| Name: |
Dataguard archivelog apply gap |
| Platform: |
Oracle |
| Category: |
Cluster and Replication |
| Description: |
Records the load memory of RAC active sessions over time. |
| Long description: |
|
| Version: |
1.32 |
| Default schedule: |
15m |
| Requires engine install: |
No |
| Compatibility tag: |
.[type=‘instance’ & databasetype=‘oracle’ & ten_and_above=‘1′ & is_pluggdb !=1] |
Parameters
| Name |
Default value |
Description |
| warning_lag_num |
10 |
Warning status if x archive logs are not applied to standby |
| alarm_lag_num |
20 |
Alarm status if x archive logs are not applied to standby |
Job Summary
- Purpose: The purpose of this job is to monitor the archive sequence apply lag on an Oracle Dataguard standby node.
- Why: This monitoring is important because a significant lag in applying archive logs can indicate replication issues or potential data loss risks in Oracle Dataguard environments, crucial for disaster recovery and high availability scenarios.
- Manual checking: You can manually check the archive sequence apply lag in the database by issuing the following SQL command:
select count(*) from v$archived_log where applied = 'NO'
Job Details
- Job Name: Oracle Dataguard Archive Sequence Apply Lag Monitoring
- Database Type: Oracle
- Category: Cluster and Replication
- Scheduled Execution: Every 10 minutes
- Description: This job checks for the number of archive logs that have not yet been applied to the standby Dataguard node. Notifications are triggered based on predefined thresholds for warning and alarm conditions.
Threshold Settings
| Threshold |
Description |
| Warning |
Triggers a warning if the number of unapplied archive logs exceeds the “warning_lag_num” parameter (Default: 10 logs). |
| Alarm |
Raises an alarm if the number of unapplied archive logs surpasses the “alarm_lag_num” parameter (Default: 20 logs). |
Implementation Notes
- Express Install: Enabled true which implies the job is crucial and prioritized for quick deployments.
- Installation Conditions: The job is installed only on Oracle instances having physical standby configuration with necessary privileges to read from the `v$archived_log` view as validated by the installation filters.
- Data Checking: SQL and JavaScript engines are used for determining the count of unapplied logs and setting the respective status based on the log count.
Reporting Template Details
- Report Title: Dataguard Archive Sequence Apply Lag Status
- Frequency: Report is generated every minute
- Report Details: The report showcases the current status of archive sequence apply lag on Oracle Dataguard.
- Report Visualization: The report includes a detailed table presentation showing the number of logs behind and current status.
Technical Details
- Value Determination: SQL query `select count(*) from v$archived_log where applied = ‘NO’` fetches the count of unapplied logs.
- Status Determination: A JavaScript script evaluates if the fetched count exceeds set thresholds, setting the status accordingly, with an immediate reflection in the monitoring dashboard.
The monitoring setup leverages both predefined system properties and customized scripts, ensuring robust oversight over critical disaster recovery components in Oracle Dataguard environments.