参考自19c Oracle® Data Guard Concepts and Administration
page114页，希望对你有帮助：

Redo received from another Oracle database via redo transport is written to the
current standby redo log group by a remote file server (RFS) foreground process.
When a log switch occurs on the redo source database, incoming redo is then written
to the next standby redo log group, and the previously used standby redo log group is
archived by an ARCn background process.

Redo received by a standby database is written directly to an archived redo log file if a
standby redo log group is not available or if the redo was sent to resolve a redo gap.
When this occurs, redo is written to the location specified by the LOCATION attribute of
one LOG_ARCHIVE_DEST_n parameter that is valid for archiving redo received from
another database. The LOG_ARCHIVE_DEST_n parameter that is used for this purpose is
determined when the standby database is mounted, and this choice is reevaluated
each time a LOG_ARCHIVE_DEST_n parameter is modified.

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