DataGuard Process Architecture

As shown in the figure below, the Data Guard operations involve many processes.



Let us see what each process is used for one by one,

In the Primary Site,

LGWR or ARCH: The redolog/archivelog from the primary database is shipped to the standby database site through LGWR/ARCH processes.

FAL (Fetch Archive Log): When there is a communication loss between primary and standby (for example, network failure), the log shipping is affected and there may be gaps. When the communication is established again the FAL processes enable the automatic gap resolution and resynchronization process.

In the Standby Site,

RFS (Remote File Server): The RFS process receives the redo records from the Primary site.

MRP (Managed Recovery Process): MRP applies the redo records to the Physical Standby databases.

LSP (Logical Standby Process): The LSP process translates the redo records in to SQL and fires the SQL to the logical standby databases.

If Data Guard Broker is enabled then DMON Process is enabled on both the primary and standby sites.

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