Mirror Replication Agent provides features for both automatic and manual log truncation.
Mirror Replication Agent provides two options for automatic transaction log truncation:
Periodic truncation, based on a time interval you specify
Automatic truncation whenever Mirror Replication Agent receives a new LTM Locator value from the primary Replication Server
You also have the option to switch off automatic log truncation. By default, automatic log truncation is enabled and is set to truncate the log whenever Mirror Replication Agent receives a new LTM locator value from the primary Replication Server.
When pdb_include_archives is set to true, the default, and pdb_remove_archives is set false, Mirror Replication Agent does not perform any online or archived transaction log truncation. When pdb_include_archives is set to true, the default, and pdb_remove_archives is set true, Mirror Replication Agent deletes from the pdb_archive_path location the archive redo logs that have already been processed. The Mirror Replication Agent is not responsible for archiving online transaction logs.
Sybase recommends that you configure Mirror Replication
Agent to remove archive log files only if an additional archive
log directory is used.
When the configuration parameter pdb_include_archives is set to false, Mirror Replication Agent performs online redo log truncation (either scheduled or manual) by issuing the alter system command with the archive log sequence keywords. The command uses the log sequence number of the redo log file whose contents have been processed by Mirror Replication Agent and are ready to be archived.
The alter system command syntax in
Oracle allows redo log files to be archived in addition to the single
log sequence specified in the command. To avoid the possibility
of unintentional archiving, Mirror Replication Agent only issues
this command when it is processing the redo log file whose status
is current.
You can specify the automatic truncation option you want (including none) by using the ra_config command to set the value of the truncation_type configuration parameter.
If you want to truncate the transaction log automatically based on a time interval, use the ra_config command to set the value of the truncation_interval configuration parameter.
You can truncate the Mirror Replication Agent transaction log manually, at any time, by invoking the pdb_truncate_xlog command at the Mirror Replication Agent administration port.
