Generally, the Mirror Replication Agent default configuration values provide optimal performance. However, there may be certain situations where the configuration should be changed to suit or optimize your particular environment.
By default, the system logs produced by the Mirror Replication Agent are a pre-set size. They roll over occasionally to prevent continual disk consumption.
You can adjust the size of a log and adjust the number of backup files:
By increasing these sizes, you can save log data for a longer period of time.
By decreasing them, you can increase the unused space in your environment.
Adjusting the size and volume of log files
Log in to the running Mirror Replication Agent instance using the administrator login.
Verify that the Mirror Replication Agent instance is in Admin state:
ra_status
Use the ra_config command to set the values of the following Mirror Replication Agent configuration parameters for the primary database. Increase the following values if you want to increase the size and number of backup files. Decrease the following values if you want to make more space available in your environment:
ra_config log_backup_files, n
ra_config log_wrap, m
Mirror Replication Agent uses the configuration parameters scan_sleep_increment and scan_sleep_max to “pause” scanning when the end of the log is reached. This prevents Mirror Replication Agent from continually “spinning” on the end of the log. The downside is that Mirror Replication Agent may pause up to 60 seconds (by default) before a new transaction appears because it was sleeping. When you need the maximum possible latency for a transaction to be less than the 60-second default, you can reduce the scan parameters. This results in additional CPU usage when the end of the log is reached.
Conversely, if CPU maximization is a greater concern than latency, you can increase these parameters to allow Mirror Replication Agent to use less CPU on an inactive log, at the cost of having the latency of the “next” transaction increased.
These parameters have effect only when the end of the
log has been reached and there is no additional activity to be replicated.
By default, Mirror Replication Agent immediately re-scans (without
pause) when the end of the log has not been reached.
