Progress Fathom Replication
User’s Guide

> ## Overview of implementation tasks for deferred agent startup

> You can configure Fathom Replication to allow database activity sooner by setting the `defer-agent-startup` property in the `[server]` section of the property file. If you set `defer-agent-startup` to a valid non-zero time-out value, the source database can be active before the Fathom Replication server even contacts its configured agent(s).

> In addition, the deferred agent startup mode allows you to create a target database by doing an online backup of the source database. With the default implementation, the source database must be shut down while you perform the backup. See the "Setting up the source database (online backup)" section for more information.

> To utilize this configuration, the `defer-agent-startup` property must be specified for the Fathom Replication server in the `[server]` section of the property file. For more information on this property and its values, see the "Server properties" section and the "Fathom Replication properties files" section.

> This implementation configures the Fathom Replication server to do the following:

> - If the Fathom Replication server cannot connect to its configured agent(s) on the first connection attempt, it will go into deferred agent startup mode.

> - While in deferred agent startup mode, the Fathom Replication server will wait five minutes and then attempt agent connection again.

> - The Fathom Replication server attempts to connect every five minutes until all agent(s) are connected, or until the time-out specified in the `defer-agent-startup` expires.

> Note: If you do not want to wait the five minutes for the server to attempt connection to the agents, you can force agent connection using the `startAgent` command of the `DSRUTIL` utility. For more information, see the "DSRUTIL utility" section.
> To cancel `derfer-agent-startup`, use the `cancelDefer` command of the `DSRUTIL` utility.

> - Once the agent(s) are connected to, startup, initialization, and synchronization are performed.

> - During the entire connection process, source database activity continues to occur, but will be halted briefly while the Fathom Replication server reinserts itself into normal RDBMS AI block processing.

> To implement Fathom Replication with deferred agent startup:

> 1. Execute your `PROENV` and `DSRENV` scripts every time you open a command-line window or shell, and ensure that you have `$DLC`, `$PROMSGS`, `$DSRHOME`, and `$PROCFG` environment variables set correctly.

> 2. Shut down the source database.

> 3. On the source machine, do the following:

> 1. Create an initial backup of your source database.
> Note: Step a is not necessary if you prefer to do an online backup of the source database. Online backup is preferable in situations where the database is large, backups are time consuming, and you want to minimize the down-time of the database. For more information, see the "Setting up the source database (online backup)" section.

> 2. Create a structure file (`.st`) of the source database.
> 3. Ensure After Imaging is set up and running.
> 4. Enable the source database for Fathom Replication.
> 5. Perform an incremental backup of the source database.
> Note: Step e is not necessary if you intend to create an online backup. See the "Setting up the source database (online backup)" section.

> 4. Configure your Fathom Replication server by doing the following:

> 1. Configure the Fathom Replication server properties file to set the `defer-agent-startup` property to a valid time-out value.
> 2. Configure the Fathom Replication server properties file for your other server properties.

> For more information, see the "Configuring the Fathom Replication server" section and the "Fathom Replication properties" section.

> 5. Start the source database.

> 6. If you have not already created an offline backup, create an online backup of the source database.

> 7. On the target machine do the following:

> 1. Use the source database backup as an initial copy of the target database.
> 2. Enable the target database for Fathom Replication.

> For more information about these tasks, see the "Setting up the target database" section.

> 8. Configure Fathom Replication agent properties file.

> 9. Start the Fathom Replication target database.

> 10. Wait for the Fathom Replication server to connect to the agent(s), or use `DSRUTIL startAgent` for force a connection without waiting. For more information on `startAgent,` see Table 3–4.

> Once the synchronization between the Fathom Replication server and agent(s) is complete, normal Fathom Replication target database activity is allowed.

> ##### Special considerations for deferred agent startup

> Schema updates are not allowed while the Fathom Replication server is performing synchronization. If schema are being performed when failure recovery synchronization begins, source database updates will block until failure recovery is complete.

> Source database activity cannot continue without the agent(s) connected when synchronous replication is being used.

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