Replication Agent can be in any of several states:
Admin – the instance has no connections established to other replication system components but is available to execute administrative commands, such as changing configuration parameters and maintaining the transaction log or the RASD. No replication processing occurs when the Replication Agent instance is in Admin state.
Replicating – the instance is performing its normal replication processing: scanning the transaction log, processing log records and change-set data, and sending LTL commands to the primary Replication Server. Some administrative commands are not allowed.
Replicating (Resynchronization) – the instance has been restarted and is resynchronizing the primary and replicate databases.
Replication Down – replication has stopped due to an error.
From the moment a state-changing event occurs until the Replication Agent instance is actually in the new state, the instance is said to be “in transition.” During state transition, some administrative commands are ignored.
In Admin state, the Replication Agent instance is running but has no connection established to the primary Replication Server (or RSSD, if so configured) or the primary database.
You can perform most administrative tasks while the Replication Agent instance is in Admin state, including changing the value of any Replication Agent configuration parameter.
In Replicating state, the Replication Agent instance maintains a connection to the primary database and to the primary Replication Server (and RSSD, if so configured), and its Log Reader component scans the transaction log for transactions to replicate.
The Log Reader component log-scanning process “sleeps” according to the values of the scan_sleep_increment and scan_sleep_max configuration parameters.
After the Log Transfer Interface (LTI) component finishes processing all of the change sets it received from the Log Reader and sending all of the LTL to the Replication Server, no replication throughput occurs until new replicated transactions appear in the log and the Log Reader scans them.
The Replication Agent instance remains in Replicating state, unless some other event causes it to go to Admin or Replication Down state.
Replication Agent goes into the Replicating (Resynchronization) state after the resume resync command is invoked and completes successfully. This state indicates the Replication Agent is resynchronizing the primary and replicate databases. When Replication Agent has completed resynchronizing the primary and replicate databases, it returns to the Replicating state. For information on resynchronization, see the Replication Server Heterogeneous Replication Guide and the Replication Server Administration Guide. For information on the resume command, see the Replication Agent Reference Manual.
When Replication Agent drops a connection, before it goes to Replication Down state, it first attempts to reestablish the connection using the values recorded in its configuration parameters for that connection. If it cannot reconnect, the Replication Agent instance goes to Replication Down state.
After the error has been resolved, Replication Agent may return to the Replicating state.