The methodology in Redo Apply Troubleshooting and Tuning. If you see no transport lag but a high redo apply lag, address the apply lag using Investigation with Gather Information to Troubleshoot Transport Lag. If you observe a high redo transport lag, continue this redo transport Name like '%lag' and count >0 order by LAST_TIME_UPDATED SQL> select NAME,TIME,UNIT,COUNT,LAST_TIME_UPDATED from V$STANDBY_EVENT_HISTOGRAM where V$STANDBY_EVENT_HISTOGRAM at the beginning of the time period andĬompare that snapshot with one taken at the end of the time period. To evaluate the transport or apply lag over a time period, take a snapshot of SQL> select * from v$standby_event_histogram where name like '%lag' and count Standby instance was last started, query the V$STANDBY_EVENT_HISTOGRAM To obtain a histogram that shows the history of transport or apply lag values since the The last datum time from V$DATAGUARD_STATS to the current time on the The potential data loss in this scenario would be from This column across multiple queries indicates that the standby database is not receivingĭata from the primary database. The lag metrics are computed based onĭata that is periodically received from the primary database. The DATUM_TIME column is the local time on the standby database when theĭatum used to compute the metric was received. SQL> select name,value,time_computed,datum_time from v$dataguard_stats where To determine if there is any lag on the standby database, and if this is a transport orĪpply lag, query the V$DATAGUARD_STATS view. Tuning and Troubleshooting Synchronous Redo Transport.Advanced Troubleshooting: Determining Network Time with Asynchronous Redo Transport.Evaluate the Transport Network and Tune.Compare Redo Generation Rate History on the Primary.Gather Information to Troubleshoot Transport Lag.Verify Transport Lag and Understand Redo Transport Configuration.Necessary data to assess whether there is indeed a redo transport problem and what canīe tuned to optimize redo transport throughput. Methodology described in the topics below, which guide you through gathering the To improve transport holistically, leverage the data gathering and troubleshooting As a prerequisite, ensure that the Oracle Data Guard Configuration Best Practices are implemented. The guidance presented here assumes that the MAA configuration best practices areįollowed. Performance of the primary and standby systems, the network that connects them, and the I/Oįor most Oracle Data Guard configurations, you should be able to achieve zero or minimalĭata loss by troubleshooting and tuning redo transport. Oracle Data Guard redo transport performance is directly dependent on the (MAA) best practices have shown that switchover and failover can be reduced to Using a physical standby database and Oracle Maximum Availability Architecture Role transitions can effectively minimize downtime and ensure that the databaseĮnvironment is restored with minimal impact on the business. With proper planning and implementation, Oracle Data Guard and Active Data Guard However, as applicationsĪnd databases increase in size and throughput, media recovery operations canīenefit from additional tuning to further optimize recovery time or redo apply Media recovery when the standby is always up to date. In most cases, the default Oracle settings result in satisfactory performance for Impact and distribute resources appropriately. However, using sound MAA recommended methods, you can monitor and assess the Synchronous redo transport does sacrifice some performance for zero data loss Sufficient for handling the workload, and that you monitor those resources for Tuning asynchronous redo transportĬonsists mainly of ensuring that the primary, standby, and network resources are However, if you observe performance issues, you can monitor and tune redoĪsynchronous redo transport with Maximum Performance data protection mode is theĭefault Oracle Data Guard configuration. Oracle Data Guard automatically tunes redo transport to optimize performance. Evaluate the adherence to those best practices before doing any The assumption when assessing and tuning is that all of the Oracle Database andĭata Guard configuration best practices are already integrated in theĮnvironment. The following Oracle MAA best practices for monitoring, assessment, and performanceĮnsure that Oracle Database and Oracle Data Guard configuration best practices To get the best performance from your Oracle Data Guard configuration, use
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