The primary Replication Server maintains a “locator” value (LTM locator) that identifies the last point in a transaction log from which all data has been successfully received by the primary Replication Server.
The Replication Agent periodically requests this value from the Replication Server connection to identify a position in the transaction log, which can then be used to identify where older data can be released or removed from the log.
There is a performance trade-off in determining how often to request an LTM locator update. Frequent queries of the LTM locator value from a Replication Server can slow down replication (the Replication Agent must stop sending LTL commands long enough to request and receive the LTM locator value) while it provides more frequent opportunities to release data from the primary database transaction log. When restarting, the Replication Agent must re-send all data in the log that exists since the last LTM locator value was received from Replication Server.
Generally, if replication throughput performance is a priority, acquire enough log resource to allow less frequent log truncation and less frequent retrieval of the LTM locator value. If log resources are scarce, more frequent retrieval of the LTM locator value and more frequent truncation may be necessary.
For more information about using the LTM locator, see the appropriate Replication Agent documentation.