The most important Data Guard Background processes
- Fetch Archive
Log (FAL) Client - Pulls archived redo log
files from the primary site. Initiates transfer of archived redo logs when
it detects a gap sequence.
- Remote File
Server (RFS) - Receives archived and/or
standby redo logs from the primary database. the Remote File Server (RFS)
process receives the redo data and writes it to a Standby Redo Log (SRL).
RFS sends an acknowledgement back to the production database that the redo
has been received and written to disk. When the production database
receives this acknowledgement, it acknowledges the commit to the client
application and processes the next transaction.
- Archiver
(ARCn) Processes - Archives the standby redo
logs applied by the managed recovery process (MRP).
- Managed
Recovery Process (MRP) -
Applies archive redo log information to the standby database.
- Logical
Standby Process (LSP) - The
LSP applies the redo records from archived redo logs to the logical
standby database. The Oracle database log miner engine is used by the
logical standby process for the SQL apply operations. Using the log miner
engine, the LSP process recreates the SQL statements from redo logs that
have been executed on the primary database. These statements are then
applied to the standby database to keep it current with the primary
database.
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