Data Guard Transport & Apply Lag (Felaket Kurtarma Gecikmesi)

The measured latency between primary redo generation and its transmission (Transport Lag) or physical recovery execution (Apply Lag) on the Data Guard standby.

Internal Architecture Breakdown

Data Guard reliability relies on two separate lag components:

•Transport Lag: Redo transfer delay across the network, dictating potential data loss (RPO).
•Apply Lag: Media recovery delay on the standby host, dictating switchover and failover recovery durations (RTO).

High apply lag stems from inadequate standby CPU, storage IOPS bottlenecks, or single-threaded redo apply limits.

Production Inspection Queries

Oracle

SELECT name, value, unit, time_computed FROM v$dataguard_stats WHERE name IN ('transport lag', 'apply lag');

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